Computed tomography apparatus and method using plurality of light sources

ABSTRACT

A computed tomography (CT) apparatus includes a gantry with a first rotation device and a second rotation device, a plurality of light sources configured to emit X-rays to a subject, a detector configured to detect X-rays passing through the subject, and one or more processors. The one or more processors may be configured to rotate the first rotation device in a first rotation direction by an angle of rotation determined based on a total number of the plurality of light sources, emit X-rays to the subject by using at least one of the plurality of light sources and detect X-rays passing through the subject during the rotation of the first rotation device in the first rotation direction, and rotate the first rotation device by the determined angle of rotation in a second rotation direction.

TECHNICAL FIELD

The present disclosure relates to a computed tomography (CT) apparatusand method using a plurality of light sources.

BACKGROUND

Computed tomography (CT) is a non-invasive biometric imaging method. ACT apparatus is capable of obtaining a CT image of a subject by emittingX-rays to the subject in various directions, detecting some X-rayspassing through the subject by a detector, converting output data of thedetector into an electric signal, and reconstructing an image. Ingeneral, a CT apparatus is capable of obtaining a three-dimensional (3D)image of a subject by placing the subject in a ring-shaped gantry inwhich X-ray sources are arranged, emitting X-rays to the subject duringrotation of the gantry to obtain images of cross sections of thesubject, and reconstructing the images of the cross sections of thesubject.

SUMMARY

A computed tomography (CT) apparatus using one light source (e.g., anX-ray source) emits X-rays to a subject while rotating around thesubject by 360 degrees to obtain a CT image of the subject. When anangle of rotation of the gantry in which the light source is disposedincreases, lines (e.g., lines for supplying power to the light source)connected to the gantry may be twisted.

Because high power is needed to emit X-rays from a light source, a CTapparatus using a plurality of light sources may not be capable ofoperating the plurality of light sources simultaneously. In this case, aCT image of a subject may be obtained by appropriately setting anarrangement of the plurality of light sources and an order of emittingX-rays.

Various embodiments of the present disclosure provide a CT apparatusincluding a gantry with a first rotation device and a second rotationdevice that have a ring shape, share one axis of rotation, and arerotatable independently of each other, a plurality of light sourcesarranged on the first rotation device at regular intervals andconfigured to emit X-rays to a subject, a detector arranged on thesecond rotation device and configured to detect X-rays passing throughthe subject, and one or more processors. According to variousembodiments, the one or more processors may be configured to rotate thefirst rotation device in a first rotation direction by an angle ofrotation determined based on a total number of the plurality of lightsources, emit X-rays to the subject by using at least one of theplurality of light sources and detect X-rays passing through the subjectby the detector during the rotation of the first rotation device in thefirst rotation direction, and rotate the first rotation device by thedetermined angle of rotation in a second rotation direction opposite tothe first rotation direction.

The CT apparatus according to various embodiments of the presentdisclosure includes the plurality of light sources to emit X-rays to thesubject and thus can reduce a range of angle of rotation of the gantry.Because the range of angle of rotation of the gantry can be reduced, thestability of the CT apparatus can increase.

In the CT apparatus according to various embodiments of the presentdisclosure, an order of emitting X-rays from the plurality of lightsources can be set according to the total numbers and positions of thelight sources and the detector, and thus a CT image of the subject canbe obtained by an optimum photography method according to the structureof the CT apparatus.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a computed tomography (CT) apparatusaccording to various embodiments of the present disclosure.

FIG. 2 is a diagram illustrating a CT apparatus according to variousembodiments.

FIGS. 3A and 3B are diagrams illustrating a method of obtaining acircular CT image of a subject according to various embodiments of thepresent disclosure.

FIG. 4 is a diagram illustrating a method of obtaining a helical CTimage of a subject according to various embodiments of the presentdisclosure.

FIG. 5 is a diagram illustrating a CT apparatus according to a firstembodiment, and FIG. 6 is a cross-sectional view of an x-y plane of agantry according to the first embodiment.

FIG. 7 is a graph showing a CT method performed by the CT apparatusaccording to the first embodiment.

FIG. 8 is a graph showing a CT method performed by the CT apparatusaccording to the first embodiment.

FIG. 9 is a flowchart of operations of the CT apparatus according to thefirst embodiment.

FIG. 10 is a cross-sectional view of an x-y plane of a gantry of a CTapparatus according to a second embodiment.

FIG. 11 is a graph showing a CT method performed by the CT apparatusaccording to the second embodiment.

FIG. 12 is a graph showing a CT method performed by the CT apparatusaccording to the second embodiment.

FIG. 13 is a graph showing a CT method performed by the CT apparatusaccording to the second embodiment.

FIG. 14 is a flowchart of operations of the CT apparatus according tothe second embodiment.

FIG. 15A is a cross-sectional view of an x-y plane of a gantry of a CTapparatus according to a third embodiment, and FIG. 15B is across-sectional view of a y-z plane of the gantry according to the thirdembodiment.

FIG. 16 is a graph showing a CT method performed by the CT apparatusaccording to the third embodiment.

FIG. 17 is a cross-sectional view of an x-y plane of a gantry of a CTapparatus according to a fourth embodiment.

FIG. 18 is a graph showing a CT method performed by the CT apparatusaccording to the fourth embodiment.

FIG. 19 is a graph showing a CT method performed by the CT apparatusaccording to the fourth embodiment.

FIG. 20 is a graph showing a CT method performed by the CT apparatusaccording to the fourth embodiment.

FIG. 21 is a flowchart of operations of the CT apparatus according tothe fourth embodiment.

FIG. 22 is a cross-sectional view of an x-y plane of a gantry of a CTapparatus according to a fifth embodiment.

FIG. 23 is a graph showing a CT method performed by the CT apparatusaccording to the fifth embodiment.

FIG. 24 is a graph showing a CT method performed by the CT apparatusaccording to the fifth embodiment.

FIG. 25 is a graph showing a CT method performed by the CT apparatusaccording to the fifth embodiment.

FIG. 26 is a flowchart of operations of the CT apparatus according tothe fifth embodiment.

FIG. 27A is a cross-sectional view of an x-y plane of a gantry of a CTapparatus according to a sixth embodiment, and FIG. 27B is across-sectional view of a y-z plane of the gantry according to the sixthembodiment.

FIG. 28 is a graph showing a CT method performed by the CT apparatusaccording to the sixth embodiment.

FIG. 29 is a graph showing a CT method performed by the CT apparatusaccording to the sixth embodiment.

FIG. 30 is a flowchart of operations of the CT apparatus according tothe sixth embodiment.

FIGS. 31A and 31B are diagrams illustrating a method of adjusting avisible area of a CT apparatus.

FIG. 32 is a diagram showing a method of adjusting a visible area usinga plurality of light sources.

FIG. 33 is a diagram illustrating a CT apparatus according to variousembodiments.

FIG. 34A is a cross-sectional view of an x-y plane of a gantry of a CTapparatus according to various embodiments, and FIG. 34B is a schematiccross-sectional view of a y-z plane of the gantry.

FIG. 35A is a cross-sectional view of an x-y plane of a gantry of a CTapparatus according to various embodiments, and FIG. 35B is a schematiccross-sectional view of a y-z plane of the gantry.

DETAILED DESCRIPTION

Embodiments of the present disclosure are illustrated for describing thetechnical spirit of the present disclosure. The scope of the claimsaccording to the present disclosure is not limited to the embodimentsdescribed below or to the detailed descriptions of these embodiments.

All technical or scientific terms used herein have meanings that aregenerally understood by a person having ordinary knowledge in the art towhich the present disclosure pertains, unless otherwise specified. Theterms used herein are selected only for more clear illustration of thepresent disclosure and are not intended to limit the scope of claims inaccordance with the present disclosure.

The expressions “include,” “provided with,” “have,” and the like usedherein should be understood as open-ended terms including thepossibility of inclusion of other embodiments, unless otherwisementioned in a phrase or sentence including the expressions.

A singular expression may include the plural meaning, unless otherwisementioned, and the same is applicable to a singular expression stated inthe claims.

The terms “first,” “second,” etc. used herein are used to identify aplurality of components from one another and are not intended to limitthe order or importance of the relevant components.

The term “unit” used in these embodiments means a software component orhardware component, such as a field-programmable gate array (FPGA) andan application specific integrated circuit (ASIC). However, a “unit” isnot limited to software and hardware. A “unit” may be configured to bestored in an addressable storage medium or may be configured to operateone or more processors. For example, a “unit” may include components,such as software components, object-oriented software components, classcomponents, and task components, as well as processors, functions,attributes, procedures, subroutines, segments of program codes, drivers,firmware, micro-codes, circuits, data, databases, data structures,tables, arrays, and variables. Functions provided in components and“units” may be combined into a smaller number of components and “units”or further subdivided into additional components and “units.”

The expression “based on” used herein is used to describe one or morefactors that influence a decision, an action of judgment or an operationdescribed in a phrase or sentence including the relevant expression, andthis expression does not exclude additional factors influencing thedecision, the action of judgment, or the operation.

When a certain component is described as “coupled to” or “connected to”another component, this should be understood as meaning that the certaincomponent may be coupled or connected directly to the other component orthat the certain component may be coupled or connected to the othercomponent via a new intervening component.

Hereinafter, embodiments of the present disclosure will be describedwith reference to the accompanying drawings. In the accompanyingdrawings, identical or corresponding components are indicated byidentical reference numerals. In the following description ofembodiments, repeated descriptions of the identical or correspondingcomponents will be omitted. However, even when a description of acomponent is omitted, such a component is not intended to be excludedfrom an embodiment.

FIG. 1 is a block diagram of a computed tomography (CT) apparatus 100according to various embodiments of the present disclosure.

Referring to FIG. 1, the CT apparatus 100 according to variousembodiments may include a processor 110 and a gantry 120. The CTapparatus 100 according to various embodiments may further include atransfer unit 150 and a power supply device 160. Even when some of thecomponents shown in FIG. 1 are omitted or replaced with othercomponents, there will be no difficulties in implementing variousembodiments set forth herein.

The processor 110 according to various embodiments may be a componentthat controls the components of the CT apparatus 100 and/or performs anoperation for communication or data processing. The processor 110 may beoperatively connected to, for example, the components of the CTapparatus 100. The processor 110 may load a command or data receivedfrom another component of the CT apparatus 100 to a memory (not shown),process the command or data stored in the memory, and store result data.The CT apparatus 100 according to various embodiments may include one ormore processors 110.

The gantry 120 according to various embodiments may be a structure inwhich a plurality of light sources 130 and a detector 140 are arranged.The gantry 120 may be a ring-shaped (or tunnel type) structureconfigured to rotate the plurality of light sources 130 and the detector140 about a certain axis.

The light source 130 according to various embodiments may be an X-raysource for emitting X-rays. The light source 130 may emit X-rays to asubject under control of the processor 110. The subject may be located,for example, in a bore (or an inner hole) of the gantry 120. The CTapparatus 100 according to various embodiments may include a pluralityof light sources 130. The plurality of light sources 130 may be, forexample, X-ray sources using carbon nanotubes (CNTs).

The detector 140 according to various embodiments may be an X-raydetector 140 for detecting the amount (or intensity) of X-rays. Thedetector 140 may detect the amount of X-rays passing through a subjectamong X-rays emitted to the subject from the light source 130. When adensity in the subject is not uniform, the amount of X-rays absorbed bythe subject may vary according to a direction in which the X-rays areemitted. The detector 140 may measure a reduction rate of the amount ofX-rays passing through the subject when the X-rays are emitted atvarious angles, and the processor 110 may determine a density in thesubject based on data measured by the detector 140 and create athree-dimensional (3D) image by reconstructing cross sections of theinside of the subject using the determined density in the subject. TheCT apparatus 100 according to various embodiments may include at leastone detector 140.

The CT apparatus 100 according to an embodiment may include a gantry120, a plurality of light sources 130, and a detector 140. The gantry120 may include a first rotation device and a second rotation devicethat have a ring shape, share an axis of rotation, and are rotatableindependently of each other. The plurality of light sources 130 may bearranged on the first rotation device at regular intervals, and thedetector 140 may be arranged on the second rotation device. For example,the plurality of light sources 130 may be arranged on an inner side ofthe first rotation device at regular intervals to emit X-rays to thesubject in the gantry 120. For example, the detector 140 may beconfigured to surround all of the inner sides of the second rotationdevice. In this case, even when X-rays are emitted from one of theplurality of light sources 130, the detector 140 may detect X-rayspassing through the subject.

The CT apparatus 100 according to an embodiment may include a gantry120, a plurality of light sources 130, and a plurality of detectors 140.The gantry 120 may include a ring-shaped rotation device rotatable aboutan axis of rotation. The plurality of light sources 130 may be arrangedon the rotation device at regular intervals. Each of the plurality ofdetectors 140 may be arranged at a position facing and corresponding toone of the plurality of light sources 130. The plurality of lightsources 130 may emit X-rays to a subject loaded on the transfer unit150, and the plurality of detectors 140 may detect X-rays passingthrough the subject. The plurality of light sources 130 may be locatedat the same position on an axis of rotation of the rotation device. Forexample, the plurality of light sources 130 may be located at the sameposition on a z-axis.

The CT apparatus 100 according to an embodiment may include a gantry120, a plurality of light sources 130, and a plurality of detectors 140.The gantry 120 may include a ring-shaped rotation device rotatable aboutan axis of rotation. The plurality of light sources 130 may be arrangedon the rotation device at regular intervals. Each of the plurality ofdetectors 140 may be arranged at a position facing and corresponding toone of the plurality of light sources 130. The plurality of lightsources 130 may be arranged at positions on an axis of rotation of therotation device to be spaced a certain distance from each other. Forexample, positions of the plurality of light sources 130 on the z-axismay be different from each other.

The CT apparatus 100 according to an embodiment may include a gantry120, a plurality of light sources 130, and a detector 140. The gantry120 may include a ring-shaped rotation device rotatable about an axis ofrotation. The gantry 120 may be divided into a first sub-device and asecond sub-device. The plurality of light sources 130 may be arranged onthe first sub-device to be spaced a certain distance from each other.The detector 140 may be arranged on the second sub-device.

The CT apparatus 100 according to an embodiment may include a gantry120, a plurality of light sources 130, and a detector 140. The gantry120 may include a first rotation device and a second rotation devicethat have a ring shape, share an axis of rotation, and are rotatableindependently of each other. The plurality of light sources 130 may bearranged on the first rotation device at regular intervals. The detector140 may be arranged in a region of the second rotation device.

The CT apparatus 100 according to an embodiment may include a gantry120, a plurality of first light sources 130, a plurality of lightsources 130, and a detector 140. The gantry 120 may include a firstrotation device, a second rotation device, and a third rotation devicethat have a ring shape, share an axis of rotation, and are rotatableindependently of one another. The plurality of first light sources 130may be arranged on the first rotation device at regular intervals. Theplurality of second light sources 130 may be arranged on the secondrotation device at regular intervals. The detector 140 may be arrangedin a region of the third rotation device.

The transfer unit 150 according to various embodiments may be a devicemovable in a bore of the gantry 120 having a ring shape in a directionof an axis of rotation of the gantry 120. A subject that is a computedtomography target may be loaded on the transfer unit 150.

The power supply device 160 according to various embodiments may supplypower to operate each component of the CT apparatus 100. The powersupply device 160 may supply power required to output X-rays from theplurality of light sources 130.

FIG. 2 is a diagram illustrating a CT apparatus 100 according to variousembodiments. For example, FIG. 2 is a diagram schematically showing onlycomponents indispensable for describing an operating method of the CT100.

Referring to FIG. 2, the CT apparatus 100 according to variousembodiments may include a plurality of light sources and at least onedetector, emit X-rays to a subject O using the plurality of lightsources, and detect X-rays passing through the subject O using the atleast one detector.

According to various embodiments, the subject O may be located on atransfer unit 150, and the transfer unit 150 may be moved in a directionof an axis of rotation of a gantry 120 through a bore of the gantry 120.

In order to obtain a CT image of a subject O located in the bore of thegantry 120, the CT apparatus 100 according to various embodiments mayemit X-rays to the subject O and detect X-rays passing through thesubject O using the at least one detector while the plurality of lightsources arranged on the gantry 120 are rotated about the subject O.

FIGS. 3A and 3B are diagrams illustrating a method of obtaining acircular CT image of a subject according to various embodiments of thepresent disclosure.

Referring to FIGS. 3A and 3B, the CT apparatus 100 according to variousembodiments may obtain circular CT images of different parts of asubject O and create an image of the entire subject O from a combinationof the circular CT images. The processor 110 of the CT apparatus 100 maymove the transfer unit 150, on which the subject O is loaded, by apredetermined distance and repeatedly obtain a CT image of the subject Oa predetermined number of times.

As shown in the example of FIG. 3A, the processor 110 may move thetransfer unit 150, on which the subject O is loaded, in a direction ofan axis of rotation of the gantry 120 and stop the transfer unit 150when a head part of the subject O is located in the bore. The processor110 may obtain a circular CT image of the head part of the subject Ousing a plurality of light sources 130 and at least one detector 140 ina state in which the transfer unit 150 is stopped. Thereafter, theprocessor 110 may stop the transfer unit 150 after moving the transferunit 150 by a predetermined distance. In this case, as shown in FIG. 3B,a chest part of the subject O may be located in the bore. The processor110 may obtain a circular CT image of the chest part of the subject Ousing the plurality of light sources 130 and at least one detector 140.The processor 110 may repeatedly perform the above operation a pluralityof times to obtain circular CT images of other parts of the subject Oand create an image of the entire subject O from a combination of theobtained circular CT images.

FIG. 4 is a diagram illustrating a method of obtaining a helical CTimage of a subject according to various embodiments of the presentdisclosure.

Referring to FIG. 4, the CT apparatus 100 according to variousembodiments may obtain helical CT images of a subject O and create animage of the entire subject O using the helical CT images. For example,the processor 110 of the CT apparatus 100 may move the transfer unit150, on which the subject O is loaded, constantly at a predeterminedconstant speed. The processor 110 may obtain helical CT images of thesubject O using the plurality of light sources 130 and at least onedetector 140 while the transfer unit 150 is moving at the predeterminedspeed. The processor 110 may create an image of the entire subject Ousing the helical CT images of the subject O.

First Embodiment

FIGS. 5 to 9 are diagrams for describing a CT apparatus 100 according toa first embodiment and a CT method using the same.

FIG. 5 is a diagram illustrating the CT apparatus 100 according to thefirst embodiment, and FIG. 6 is a cross-sectional view of an x-y planeof a gantry according to the first embodiment.

Referring to FIGS. 5 and 6, the CT apparatus 100 according to variousembodiments may include a gantry, a plurality of light sources 531, 533and 535, and a detector 540. The gantry may include a first rotationdevice 521 and a second rotation device 523 that have a ring shape,share an axis of rotation, and are rotatable independently of eachother. The plurality of light sources 531, 533 and 535 may be arrangedon the first rotation device 521 at regular intervals. The detector 540may be configured to surround all of the inner sides of the secondrotation device 523. The plurality of light sources 531, 533 and 535 mayemit X-rays to a subject O loaded on a transfer unit 550, and thedetector 540 may detect X-rays passing through the subject O. Althoughin these drawings it is assumed for convenience of description that atotal number of the plurality of light sources is three, the number ofthe plurality of light sources is not limited to three and may be two orgreater than three.

According to various embodiments, the processor 110 may determine aninterval between angles of the plurality of light sources 531, 533 and535 arranged on the first rotation device 521 and an angle of rotationof the first rotation device 521 based on the total number of theplurality of light sources 531, 533 and 535. The processor 110 maydetermine a value obtained by dividing 360 degrees by the total numberof the plurality of light sources 531, 533 and 535 as an intervalbetween angles of the plurality of light sources 531, 533 and 535arranged on the first rotation device 521 and as an angle of rotation ofthe first rotation device 521. For example, when the total number of theplurality of light sources 531, 533 and 535 is three, the plurality oflight sources 531, 533 and 535 may be arranged at intervals of 120degrees on the first rotation device 521, and an angle of rotation ofthe first rotation device 521 may be determined to be 120 degrees. Inthis case, even when the first rotation device 521 is rotated only by120 degrees, it is possible to create a 3D image of the subject Obecause there are three light sources arranged at intervals of 120degrees.

When the detector 540 according to various embodiments is configured tosurround all of the inner sides of the second rotation device 523, theprocessor 110 may cause the detector 540 to detect X-rays passingthrough the subject O even when X-rays are emitted to the subject O fromone of the plurality of light sources 531, 533 and 535.

FIG. 7 is a graph showing a CT method performed by the CT apparatus 100according to the first embodiment. Specifically, FIG. 7 is a graphshowing operational states of the plurality of light sources 531, 533and 535, the first rotation device 521, and the transfer unit 550 overtime when the total number of the plurality of light sources 531, 533and 535 is three.

In the graph of the first rotation device 521 among the graphs 700, anoperational state 1 may represent a state of rotation in a firstrotation direction, an operational state 0 may represent a state ofnon-rotation, and an operational state −1 may represent a state ofrotation in a second rotation direction opposite to the first rotationdirection. In the graphs of the first light source 531, the second lightsource 533, and the third light source 535 among the graphs 700, anoperational state 1 may represent a state in which X-rays are emittedand an operational state 0 may represent a state in which X-rays are notemitted. In the graph of the transfer unit 550 among the graphs 700, anoperational state 1 may represent a state of movement in a positive (+)direction of an axis of rotation, and an operational state −1 mayrepresent a state of movement in a negative (−) direction of the axis ofrotation.

The CT apparatus 100 according to various embodiments may obtaincircular CT images of different parts of a subject by an operatingmethod shown in the graphs 700 and combine the circular CT images tocreate an image of the entire subject.

The processor 110 according to various embodiments may rotate the firstrotation device 521 in the first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources 531, 533 and 535. For example, when the total number of theplurality of light sources 531, 533 and 535 is three, the angle ofrotation of the first rotation device 521 may be determined to be 120degrees. Referring to the graph of the first rotation device 521 amongthe graphs 700, the processor 110 may rotate the first rotation device521 by 120 degrees in the first rotation direction from t₁ to t₂.

The processor 110 according to various embodiments may emit X-rays tothe subject by using at least one of the plurality of light sources 531,533 and 535 during the rotation of the first rotation device 521 in thefirst rotation direction. During the rotation of the first rotationdevice 521 in the first rotation direction, the processor 110 maycontrol the plurality of light sources 531, 533 and 535 to alternatelyemit X-rays to the subject in units of a unit angle in a predeterminedorder. For example, whenever the first rotation device 521 is rotated by1 degree, it is possible to change a light source to emit X-rays in thepredetermined order.

Referring to the graphs of the first light source 531, the second lightsource 533, and the third light source 535 among the graphs 700, theprocessor 110 may control the first light source 531, the second lightsource 533, and the third light source 535 to emit X-rays to the subjectsequentially and alternately during the rotation of the first rotationdevice 521 from 0 degrees to 1 degree in the first rotation direction,i.e., from t₁ to t₁₃ For example, the processor 110 may emit X-rays tothe subject by using the first light source 531 among the plurality oflight sources 531, 533 and 535 during the rotation of the first rotationdevice 521 from 0 degrees to ⅓ degrees in the first rotation direction,i.e., t₁ to t₁₁. The processor 110 may emit X-rays to the subject byusing the second light source 533 among the plurality of light sources531, 533 and 535 during the rotation of the first rotation device 521from ⅓ degrees to ⅔ degrees, i.e., from t₁₁ to t₁₂. The processor 110may control the plurality of light sources 531, 533 and 535 such thatX-rays are emitted to the subject by using the third light source 535among the plurality of light sources 531, 533 and 535 during therotation of the first rotation device 521 from ⅔ degrees to 1 degree,i.e., from t₁₂ to t₁₃ Thereafter, the processor 110 may control theplurality of light sources 531, 533 and 535 such that the first lightsource 531, the second light source 533, and the third light source 535emit X-rays to the subject sequentially and alternately. When it isassumed that emitting X-rays sequentially from the first light source531, the second light source 533, and the third light source 535 duringthe rotation of the first rotation device 521 by 1 degree in the firstrotation direction is one sequence, the processor 110 may repeatedlyperform the sequence 120 times at an interval of 1 degree to control theplurality of light sources 531, 533 and 535 to alternately emit X-raysto the subject in the predetermined order during the rotation of thefirst rotation device 521 from 0 degrees to 120 degrees.

The processor 110 according to various embodiments may detect X-rayspassing through the subject by the detector 540 during the rotation ofthe first rotation device 521 in the first rotation direction. In thiscase, the processor 110 may create at least one raw image of the subjectbased on the X-rays detected by the detector 540. The processor 110 maycreate a 3D image of the subject based on the at least one raw image ofthe subject. In this case, the 3D image of the subject may be a circularCT image. The processor 110 according to various embodiments may rotatethe second rotation device 523 on which the detector 540 is arranged inthe same direction as the first rotation device 521 or may not rotatethe second rotation device 523 during the rotation of the first rotationdevice 521.

The processor 110 according to various embodiments may stop the firstrotation device 521 and move the transfer unit 550 by a predetermineddistance after the first rotation device 521 is rotated by a determinedangle of rotation in the first rotation direction. Referring to thegraph of the transfer unit 550 among the graphs 700, the processor 110may move the transfer unit 550 by the predetermined distance from t₂ tot₃. The processor 110 may neither operate the plurality of light sources531, 533 and 535 nor rotate the first rotation device 521 between t₂ andt₃.

The processor 110 according to various embodiments may rotate the firstrotation device by the determined angle of rotation in a second rotationdirection opposite to the first rotation direction. Referring to thegraph of the first rotation device 521 among the graphs 700, theprocessor 110 may rotate the first rotation device 521 by 120 degrees inthe second rotation direction from t₃ to t₄.

The processor 110 according to various embodiments may emit X-rays tothe subject by using at least one of the plurality of light sources 531,533 and 535 during the rotation of the first rotation device 521 in thesecond rotation direction. During the rotation of the first rotationdevice 521 in the second rotation direction, the processor 110 maycontrol the plurality of light sources 531, 533 and 535 to alternatelyemit X-rays to the subject in units of a unit angle in a predeterminedorder. For example, whenever the first rotation device 521 is rotated by1 degree, it is possible to change a light source to emit X-rays in thepredetermined order.

Referring to the graphs of the first light source 531, the second lightsource 533, and the third light source 535 among the graphs 700, theprocessor 110 may control the third light source 535, the second lightsource 533, and the first light source 531 to emit X-rays to the subjectsequentially and alternately during the rotation of the first rotationdevice 521 from 120 degrees to 119 degrees in the second rotationdirection, i.e., from t₃ to t₃₃. For example, the processor 110 may emitX-rays to the subject by using the third light source 535 among theplurality of light sources 531, 533 and 535 during the rotation of thefirst rotation device 521 from 120 degrees to

$119\frac{2}{3}$

degrees, i.e., from t₃ to t₃₁, in the second rotation direction. Theprocessor 110 may emit X-rays to the subject by using the second lightsource 533 among the plurality of light sources 531, 533 and 535 duringthe rotation of the first rotation device 521 from

$119\frac{2}{3}$

degrees to

$119\frac{1}{3}$

degrees, i.e., from t₃₁ to t₃₂. The processor 110 may control theplurality of light sources 531, 533 and 533 to emit X-rays to thesubject by using the first light source 531 among the plurality of lightsources 531, 533 and 533 during the rotation of the first rotationdevice 521 from to

$119\frac{1}{3}$

to 119 degrees, i.e., from t₃₂ to t₃₃. Thereafter, the processor 110 maycontrol the plurality of light sources 531, 533 and 535 such that thethird light source 535, the second light source 533, and the first lightsource 531 emit X-rays to the subject sequentially and alternately. Whenit is assumed that emitting X-rays sequentially from the third lightsource 535, the second light source 533, and the first light source 531during the rotation of the first rotation device 521 by 1 degree in thesecond rotation direction is one sequence, the processor 110 mayrepeatedly perform the sequence 120 times at an interval of 1 degree tocontrol the plurality of light sources 531, 533 and 535 to alternatelyemit X-rays to the subject in the predetermined order during therotation of the first rotation device 521 from 120 degrees to 0 degreesin the second rotation direction. Although it is described above withreference to this drawing that the third light source 535, the secondlight source 533, and the first light source 531 emit X-rays to thesubject sequentially and alternately during the rotation of the firstrotation device 521 in the second rotation direction, X-rays may beemitted to the subject sequentially and alternately from the first lightsource 531, the second light source 533, and the third light source 535.

According to various embodiments, the processor 110 may repeatedlyperform a predetermined number of times a cycle of rotating the firstrotation device 521 by a determined angle of rotation in the firstrotation direction, moving the transfer unit 550 by a predetermineddistance in a direction of an axis of rotation after the rotation of thefirst rotation device 521 by the determined angle of rotation in thefirst rotation direction, rotating the first rotation device 521 by thedetermined angle of rotation in the second rotation direction, andmoving the transfer unit 550 by the predetermined distance in thedirection of the axis of rotation after the rotation of the firstrotation device 521 by the determined angle of rotation in the secondrotation direction. When the cycle is repeatedly performed thepredetermined number of times, circular CT images of different parts ofthe subject may be obtained. The processor 110 may combine the obtainedcircular CT images to obtain a 3D image of the entire subject.

FIG. 8 is a graph showing a CT method performed by the CT apparatus 100according to the first embodiment. Specifically, FIG. 8 is a graphshowing operational states of the plurality of light sources 531, 533and 535, the first rotation device 521, and the transfer unit 550 overtime when the total number of the plurality of light sources 531, 533and 535 is three.

In the graph of the first rotation device 521 among the graphs 800, anoperational state 1 may represent a state of rotation in a firstrotation direction, an operational state 0 may represent a state ofnon-rotation, and an operational state −1 may represent a state ofrotation in a second rotation direction opposite to the first rotationdirection. In the graphs of the first light source 531, the second lightsource 533, and the third light source 535 among the graphs 800, anoperational state 1 may represent a state in which X-rays are emittedand an operational state 0 may represent a state in which X-rays are notemitted. In the graph of the transfer unit 550 among the graphs 800, anoperational state 1 may represent a state of movement in a positive (+)direction of an axis of rotation, and an operational state −1 mayrepresent a state of movement in a negative (−) direction of the axis ofrotation.

The CT apparatus 100 according to various embodiments may obtain helicalCT images of a subject by an operating method shown in the graphs 800and create a 3D image of the entire subject using the obtained helicalCT images.

The processor 110 according to various embodiments may rotate the firstrotation device 521 in the first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources 531, 533 and 535. For example, when the total number of theplurality of light sources is three, the angle of rotation of the firstrotation device 521 may be determined to be 120 degrees. Referring tothe graph of the first rotation device 521 among the graphs 800, theprocessor 110 may rotate the first rotation device 521 in the firstrotation direction by 120 degrees from t₁ to t₂.

The processor 110 according to various embodiments may control thetransfer unit 550 to be moved at a predetermined speed in a direction ofan axis of rotation in response to the start of the rotation of thefirst rotation device 521 in the first rotation direction. Referring tothe graph of the transfer unit 550 among the graphs 800, the processor110 may control the transfer unit 550 to be moved constantly at thepredetermined speed in a positive direction of the axis of rotation,starting from t₁.

The processor 110 according to various embodiments may emit X-rays tothe subject by using at least one of the plurality of light sources 531,533 and 535 during the rotation of the first rotation device 521 in thefirst rotation direction. During the rotation of the first rotationdevice 521 in the first rotation direction, the processor 110 maycontrol the plurality of light sources 531, 533 and 535 to alternatelyemit X-rays to the subject in units of a unit angle in a predeterminedorder. For example, whenever the first rotation device 521 is rotated by1 degree, it is possible to change a light source to emit X-rays in thepredetermined order.

Referring to the graphs of the first light source 531, the second lightsource 533, and the third light source 535 among the graphs 800, theprocessor 110 may control the first light source 531, the second lightsource 533, and the third light source 535 to emit X-rays to the subjectsequentially and alternately during the rotation of the first rotationdevice 521 from 0 degrees to 1 degree in the first rotation direction,i.e., from t₁ to t₁₃ For example, the processor 110 may emit X-rays tothe subject by using the first light source 531 among the plurality oflight sources 531, 533 and 535 during the rotation of the first rotationdevice 521 from 0 degrees to ⅓ degrees in the first rotation direction,i.e., from t₁ to t₁₁. The processor 110 may emit X-rays to the subjectby using the second light source 533 among the plurality of lightsources 531, 533 and 535 during the rotation of the first rotationdevice 521 from ⅓ degrees to ⅔ degrees, i.e., from t₁₁ to t₁₂. Theprocessor 110 may control the plurality of light sources 531, 533 and535 to emit X-rays to the subject by using the third light source 535among the plurality of light sources 531, 533 and 535 during therotation of the first rotation device 521 from ⅔ degrees to 1 degree,i.e., from t₁₂ to t₁₃. Thereafter, the processor 110 may control theplurality of light sources 531, 533 and 535 such that the first lightsource 531, the second light source 533, and the third light source 535emit X-rays to the subject sequentially and alternately. When it isassumed that emitting X-rays sequentially from the first light source531, the second light source 533, and the third light source 535 duringthe rotation of the first rotation device 521 by 1 degree in the firstrotation direction is one sequence, the processor 110 may repeatedlyperform the sequence 120 times at an interval of 1 degree to control theplurality of light sources 531, 533 and 535 to alternately emit X-raysto the subject in the predetermined order during the rotation of thefirst rotation device 521 from 0 degrees to 120 degrees.

The processor 110 according to various embodiments may detect X-rayspassing through the subject by the detector 540 during the rotation ofthe first rotation device 521 in the first rotation direction. In thiscase, the processor 110 may create at least one raw image of the subjectbased on the X-rays detected by the detector 540. The processor 110 maycreate a 3D image of the subject based on the at least one raw image ofthe subject. In this case, the 3D image of the subject may be a helicalCT image of the subject.

The processor 110 according to various embodiments may rotate the firstrotation device 521 by a determined angle of rotation in a secondrotation direction opposite to the first rotation direction after therotation of the first rotation device 521 by the determined angle ofrotation in the first rotation direction. Referring to the graph of thefirst rotation device 521 among the graphs 800, the processor 110 mayrotate the first rotation device 521 in the second rotation direction by120 degrees from t₂ to t₃. In this case, the processor 110 maycontinuously move the transfer unit 550 at a constant speed in thedirection of the axis of rotation.

The processor 110 according to various embodiments may emit X-rays tothe subject by using at least one of the plurality of light sources 531,533 and 535 during the rotation of the first rotation device 521 in thesecond rotation direction. During the rotation of the first rotationdevice 521 in the second rotation direction, the processor 110 maycontrol the plurality of light sources 531, 533 and 535 to emit X-raysto the subject in units of a unit angle sequentially and alternately ina predetermined order. For example, whenever the first rotation device521 is rotated by 1 degree, it is possible to change a light source toemit X-rays in the predetermined order.

Referring to the graphs of the first light source 531, the second lightsource 533, and the third light source 535 among the graphs 800, theprocessor 110 may control the third light source 535, the second lightsource 533, and the first light source 531 to emit X-rays to the subjectsequentially and alternately during the rotation of the first rotationdevice 521 from 120 degrees to 119 degrees, i.e., from t₂ to t₂₃, in thesecond rotation direction. For example, the processor 110 may emitX-rays to the subject by using the third light source 535 among theplurality of light sources 531, 533 and 535 during the rotation of thefirst rotation device 521 from 120 degrees to

$119\frac{2}{3}$

degrees, i.e., from t₂ to t₂₁, in the second rotation direction. Theprocessor 110 may emit X-rays by using the second light source 533 amongthe plurality of light sources 531, 533 and 535 during the rotation ofthe first rotation device 521 from

${119\frac{2}{3}\mspace{14mu}{to}\mspace{14mu} 119\frac{1}{3}},$

i.e., from t₂₁ to t₂₂. The processor 110 may control the plurality oflight sources 531, 533 and 535 to emit X-rays to the subject by usingthe first light source 531 among the plurality of light sources 531, 533and 535 during the rotation of the first rotation device 521 from

$119\frac{1}{3}$

degrees to 119 degrees, i.e., from t₂₂ to t₂₃. Thereafter, the processor110 may control the plurality of light sources 531, 533 and 535 suchthat the third light source 535, the second light source 533, and thefirst light source 531 emit X-rays to the subject sequentially andalternately. When it is assumed that emitting X-rays sequentially fromthe third light source 535, the second light source 533, and the firstlight source 531 during the rotation of the first rotation device 521 by1 degree in the second rotation direction is one sequence, the processor110 may repeatedly perform the sequence 120 times at an interval of 1degree to control the plurality of light sources 531, 533 and 535 toalternately emit X-rays to the subject in the predetermined order duringthe rotation of the first rotation device 521 from 120 degrees to 0degrees in the second rotation direction. Although it is described abovewith reference to this drawing that the third light source 535, thesecond light source 533, and the first light source 531 emit X-rays tothe subject sequentially and alternately during the rotation of thefirst rotation device 521 in the second rotation direction, X-rays maybe emitted to the subject sequentially and alternately from the firstlight source 531, the second light source 533, and the third lightsource 535.

According to various embodiments, the processor 110 may repeatedlyperform a predetermined number of times a cycle of rotating the firstrotation device 521 by a determined angle of rotation in a firstrotation direction during the movement of the transfer unit 550 at apredetermined speed in a direction of an axis of rotation and rotatingthe first rotation device 521 by the determined angle of rotation in asecond rotation direction during the movement of the transfer unit 550at the predetermined speed in the direction of the axis of rotation.When the cycle is repeatedly performed the predetermined number oftimes, helical CT images of the subject may be obtained. The processor110 may combine the obtained helical CT images to obtain a 3D image ofthe entire subject.

FIG. 9 is a flowchart 900 of operations of the CT apparatus 100according to the first embodiment.

Referring to the flowchart 900, in operation 910, the processor 110 ofthe CT apparatus 100 according to various embodiments may rotate thefirst rotation device 521 in a first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources 531, 533 and 535. The plurality of light sources 531, 533 and535 may be arranged on the first rotation device 521 at regularintervals. The determined angle of rotation may be a value obtained bydividing 360 degrees by the total number of the plurality of lightsources 531, 533 and 535. For example, when the total number of theplurality of light sources 531, 533 and 535 is three, the processor 110may rotate the first rotation device 521 by 120 degrees in the firstrotation direction.

In operation 920, the processor 110 according to various embodiments mayemit X-rays to a subject by using at least one of the plurality of lightsources 531, 533 and 535 and detect X-rays passing through the subjectby the detector 540 during the rotation of the first rotation device 521in the first rotation direction. During the rotation of the firstrotation device 521 in the first rotation direction, the processor 110may control the plurality of light sources 531, 533 and 535 toalternately emit X-rays to the subject in units of a unit angle in apredetermined order. The detector 540 may be configured to surround thesecond rotation device 523. The processor 110 may rotate the secondrotation device 523 by the determined angle of rotation in the firstrotation direction or may not rotate the second rotation device 523during the rotation of the first rotation device 521 by the determinedangle of rotation in the first rotation direction. The processor 110according to various embodiments may move the transfer unit 550, onwhich the subject is loaded, by a predetermined distance in a directionof an axis of rotation of the first rotation device 521 after therotation of the first rotation device 521 by the determined angle ofrotation in the first rotation direction.

In operation 930, the processor 110 according to various embodiments mayrotate the first rotation device 521 by the determined angle of rotationin a second rotation direction opposite to the first rotation direction.

In operation 940, the processor 110 according to various embodiments mayemit X-rays to the subject by using at least one of the plurality oflight sources 531, 533 and 535 and detect X-rays passing through thesubject by the detector 540 during the rotation of the first rotationdevice 521 in the second rotation direction. During the rotation of thefirst rotation device 521 in the second rotation direction, theprocessor 110 may control the plurality of light sources 531, 533 and535 to sequentially and alternately emit X-rays to the subject in unitsof a unit angle in a predetermined order. The processor 110 may rotatethe second rotation device 523 by the determined angle of rotation inthe second rotation direction or may not rotate the second rotationdevice 523 during the rotation of the first rotation device 521 by thedetermined angle of rotation in the second rotation direction. Theprocessor 110 according to various embodiments may move the transferunit 550, on which the subject is loaded, by a predetermined distance inthe direction of the axis of rotation of the first rotation device 521after the rotation of the first rotation device 521 by the determinedangle of rotation in the second rotation direction.

Second Embodiment

FIGS. 10 to 14 are diagrams for describing a CT apparatus 100 accordingto a second embodiment and a CT method using the same. A description ofparts of the second embodiment that are the same as those of the firstembodiment is omitted here.

FIG. 10 is a cross-sectional view of an x-y plane of a gantry of the CTapparatus 100 according to the second embodiment.

Referring to FIG. 10, the CT apparatus 100 according to variousembodiments may include a gantry, a plurality of light sources 1031,1033 and 1035 and a plurality of detectors 1041, 1043 and 1045. Thegantry may include a ring-shaped rotation device 1020 rotatable about anaxis of rotation. The plurality of light sources 1031, 1033 and 1035 maybe arranged on the rotation device 1020 at regular intervals. Theplurality of detectors 1041, 1043 and 1045 may be arranged at positionson the rotation device 1020 facing and corresponding to the plurality oflight sources 1031, 1033 and 1035 on the rotation device 1020. Theplurality of light sources 1031, 1033 and 1035 may emit X-rays to asubject loaded on the transfer unit 1050, and the plurality of detectors1041, 1043 and 1045 may detect X-rays passing through the subject.Although in this drawing, it is assumed for convenience of descriptionthat a total number of the plurality of light sources is three, thetotal number of the plurality of light sources is not limited to threeand may be two or greater than three.

According to various embodiments, the processor 110 may determine aninterval between angles of the plurality of light sources 1031, 1033 and1035 arranged on the rotation device 1020 and an angle of rotation ofthe rotation device 1020 based on the total number of the plurality oflight sources 1031, 1033 and 1035. The processor 110 may determine avalue obtained by dividing 360 degrees by the total number of theplurality of light sources 1031, 1033 and 1035 as an interval betweenangles of the plurality of light sources 1031, 1033 and 1035 arranged onthe rotation device 1020 and an angle of rotation of the rotation device1020.

When the plurality of detectors 1041, 1043 and 1045 according to variousembodiments are arranged at positions facing and corresponding to theplurality of light sources 1031, 1033 and 1035 and even when one of theplurality of light sources 1031, 1033 and 1035 emits X-rays to thesubject, the processor 110 may detect X-rays passing through the subjectby a detector at a position corresponding to the light source 1031, 1033or 1035 emitting the X-rays. For example, X-rays passing through thesubject among X-rays emitted to the subject from the first light source1031 may be detected by the first detector 1041 arranged at the positioncorresponding to the first light source 1031, X-rays passing through thesubject among X-rays emitted to the subject from the second light source1033 may be detected by the second detector 1043 arranged at theposition corresponding to the second light source 1033, and X-rayspassing through the subject among X-rays emitted to the subject from thethird light source 1035 may be detected by the third detector 1045arranged at the position corresponding to the third light source 1035.

FIG. 11 is a graph showing a CT method performed by the CT apparatus 100according to the second embodiment. Specifically, FIG. 11 is a graphshowing operational states of the plurality of light sources 1031, 1033and 1035, the rotation device 1020, and the transfer unit 1050 over timewhen the total number of the plurality of light sources 1031, 1033 and1035 is three.

In the graph of the rotation device 1020 among the graphs 1100, anoperational state 1 may represent a state of rotation in a firstrotation direction, an operational state 0 may represent a state ofnon-rotation, and an operational state −1 may represent a state ofrotation in a second rotation direction opposite to the first rotationdirection. In the graphs of the first light source 1031, the secondlight source 1033, and the third light source 1035 among the graphs1100, an operational state 1 may represent a state in which X-rays areemitted and an operational state 0 may represent a state in which X-raysare not emitted. In the graph of the transfer unit 1050 among the graphs1100, an operational state 1 may represent a state of movement in apositive (+) direction of an axis of rotation, and an operational state−1 may represent a state of movement in a negative (−) direction of theaxis of rotation.

The CT apparatus 100 according to various embodiments may obtaincircular CT images of a subject by an operation method shown in thegraphs 1100.

The processor 110 according to various embodiments may rotate therotation device 1020 in a first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources 1031, 1033 and 1035. For example, when the total number of theplurality of light sources 1031, 1033 and 1035 is three, the angle ofrotation of the rotation device 1020 may be determined to be 120degrees. Referring to the graph of the rotation device 1020 among thegraphs 1100, the processor 110 may rotate the rotation device 1020 by120 degrees from t₁ to t₂ in the first rotation direction.

Referring to the graph of the transfer unit 1050 among the graphs 1100,the processor 110 according to various embodiments may not move thetransfer unit 1050 to obtain a circular CT image of the subject.

The processor 110 according to various embodiments may emit X-rays tothe subject by using at least one of the plurality of light sources1031, 1033 and 1035 during the rotation of the rotation device 1020 inthe first rotation direction. For example, the processor 110 may controlthe plurality of light sources 1031, 1033 and 1035 to emit X-rays to thesubject from all of the plurality of light sources 1031, 1033 and 1035during the rotation of the rotation device 1020 in the first rotationdirection. For example, the processor 110 may control the plurality oflight sources 1031, 1033 and 1035 to alternately emit X-rays to thesubject in units of a unit angle in a predetermined order during therotation of the rotation device 1020 in the first rotation direction.

For example, referring to the graphs of the first light source 1031, thesecond light source 1033, and the third light source 1035 among thegraphs 1100, the processor 110 may emit X-rays to the subject using allof the first light source 1031, the second light source 1033, and thethird light source 1035 during the rotation of the rotation device 1020from 0 degrees to 120 degrees in the first rotation direction, i.e.,from t₁ to t₂.

For example, as shown in FIG. 7, the processor 110 may control theplurality of light sources 1031, 1033 and 1035 to emit X-rays to thesubject sequentially and alternately from the first light source 1031,the second light source 1033, and the third light source 1035. When itis assumed that emitting X-rays sequentially from the first light source1031, the second light source 1033, and the third light source 1035during the rotation of the rotation device 1020 by 1 degree in the firstrotation direction is one sequence, the processor 110 may repeatedlyperform the sequence 120 times at an interval of 1 degree to control theplurality of light sources 1031, 1033 and 1035 to alternately emitX-rays to the subject in the predetermined order during the rotation ofthe rotation device 1020 from 0 degrees to 120 degrees. The processor110 according to various embodiments may detect X-rays passing throughthe subject through the plurality of detectors 1041, 1043 and 1045during the rotation of the rotation device 1020 in the first rotationdirection. In this case, the processor 110 may create at least one rawimage of the subject based on the X-rays detected using the plurality ofdetectors 1041, 1043 and 1045. The processor 110 may create a 3D imageof the subject based on the at least one raw image of the subject. Inthis case, the 3D image of the subject may be a circular CT image.

FIG. 12 is a graph showing a CT method performed by the CT apparatus 100according to the second embodiment. Specifically, FIG. 12 is a graphshowing operational states of the plurality of light sources 1031, 1033and 1035, the rotation device 1020, and the transfer unit 1050 over timewhen the total number of the plurality of light sources 1031, 1033 and1035 is three.

The CT apparatus 100 according to various embodiments may obtain helicalCT images of a subject by an operation method shown in graphs 1200.

The processor 110 according to various embodiments may rotate therotation device 1020 in a first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources 1031, 1033 and 1035. For example, when the total number of theplurality of light sources 1031, 1033 and 1035 is three, the processor110 may determine the angle of rotation of the rotation device 1020 tobe 120 degrees. Referring to the graph of the rotation device 1020 amongthe graphs 1200, the processor 110 may rotate the rotation device 1020by 120 degrees from t₁ to t₂ in the first rotation direction.

The processor 110 according to various embodiments may control thetransfer unit 1050 to be moved by a predetermined distance in adirection of the axis of rotation for a predetermined time in responseto the start of the rotation of the rotation device 1020 in the firstrotation direction. Referring to the graph of the transfer unit 1050among the graphs 1200, the processor 110 may control the transfer unit1050 to be moved by the predetermined distance from t₁ to t₂ in apositive direction of the axis of rotation.

The processor 110 according to various embodiments may emit X-rays tothe subject by using one of the plurality of light sources 1031, 1033and 1035 during the rotation of the rotation device 1020 in the firstrotation direction. The processor 110 may emit X-rays to the subjectusing the first light source 1031 during the rotation of the rotationdevice 1020 in the first rotation direction from t₁ to t₂. In this case,the second light source 1033 and the third light source 1035 may notemit X-rays. The first detector 1041 disposed at the position facing andcorresponding to the first light source 1031 may detect X-rays passingthrough the subject during the emission of the X-rays from the firstlight source 1031. The processor 110 may create at least one raw imageof the subject based on the X-rays detected by the first detector 1041.

The processor 110 according to various embodiments may rotate therotation device 1020 in a second rotation direction opposite to thefirst rotation direction. The processor 110 may control the rotationdevice 1020 to be rotated by a determined angle of rotation in thesecond rotation direction after the rotation of the rotation device 1020by the determined angle of rotation in the first rotation direction.Referring to the graph of the rotation device 1020 among the graphs1200, the processor 110 may rotate the rotation device 1020 by 120degrees from t₂ to t₃ in the second rotation direction. That is, theprocessor 110 may return the rotation device 1020 to an originalposition before the rotation of the rotation device 1020 in the firstrotation direction.

The processor 110 according to various embodiments may control thetransfer unit 1050 to not be moved, i.e., to be stopped, in response tothe start of the rotation of the rotation device 1020 in the secondrotation direction. Referring to the graph of the transfer unit 1050among the graphs 1200, the processor 110 may control the transfer unit1050 not to be moved from t₂ to t₃.

The processor 110 according to various embodiments may control all ofthe plurality of light sources 1031, 1033 and 1035 not to emit X-rays tothe subject during the rotation of the rotation device 1020 in thesecond rotation direction. Referring to the graphs of the first lightsource 1031, the second light source 1033, and the third light source1035 among the graphs 1200, the processor 110 may control all of thefirst light source 1031, the second light source 1033, and the thirdlight source 1035 not to emit X-rays from t₂ to t₃.

The processor 110 according to various embodiments may repeatedlyperform rotating of the rotation device 1020 by the determined angle ofrotation in the first rotation direction and rotating of the rotationdevice 1020 by the determined angle of rotation in the second rotationdirection a number of times corresponding to the total number of theplurality of light sources 1031, 1033 and 1035.

The processor 110 according to various embodiments may rotate therotation device 1020 again by the determined angle of rotation in thefirst rotation direction. Referring to the graph of the rotation device1020 among the graphs 1200, the processor 110 may rotate the firstrotation device 1020 again by 120 degrees in the first rotationdirection from t₃ to t₄.

The processor 110 according to various embodiments may control thetransfer unit 1050 to be moved by a predetermined distance in adirection of an axis of rotation for a predetermined time in response tothe start of the rotation of the rotation device 1020 again in the firstrotation direction. Referring to the graph of the transfer unit 1050among the graphs 1200, the processor 110 may control the transfer unit1050 to be moved by a predetermined distance in a positive direction ofthe axis of rotation from t₃ to t₄.

The processor 110 according to various embodiments may emit X-rays tothe subject by using one of the plurality of light sources 1031, 1033and 1035 during the rotation of the rotation device 1020 in the firstrotation direction. The processor 110 may emit X-rays to the subject byusing the second light source 1033 during the rotation of the rotationdevice 1020 from t₃ to t₄. For example, the second light source 1033 maybe a light source closest to the first light source 1031 in the firstrotation direction. In this case, the first light source 1031 and thethird light source 1035 may not emit X-rays. The second detector 1043disposed at the position facing and corresponding to the second lightsource 1033 may detect X-rays passing through the subject during theemission of the X-rays from the second light source 1033. The processor110 may create at least one raw image of the subject based on the X-raysdetected by the second detector 1043.

The processor 110 according to various embodiments may rotate therotation device 1020 again in the second rotation direction opposite tothe first rotation direction. Referring to the graph of the rotationdevice 1020 among the graphs 1200, the processor 110 may rotate therotation device 1020 again by 120 degrees in the second rotationdirection in the second rotation direction from t₄ to t₅.

The processor 110 according to various embodiments may control thetransfer unit 1050 to not be moved, i.e., to be stopped, in response tothe start of the rotation of the rotation device 1020 again in thesecond rotation direction. Referring to the graph of the transfer unit1050 among the graphs 1200, the processor 110 may control the transferunit 1050 not to be moved from t₄ to t₅.

The processor 110 according to various embodiments may control all ofthe plurality of light sources 1031, 1033 and 1035 not to emit X-rays tothe subject during the rotation of the rotation device 1020 again in thesecond rotation direction. Referring to the graphs of the first lightsource 1031, the second light source 1033, and the third light source1035 among the graphs 1200, the processor 110 may control all of thefirst light source 1031, the second light source 1033, and the thirdlight source 1035 not to emit X-rays from t₄ to t₅.

The processor 110 according to various embodiment may perform rotatingof the rotation device 1020 in the first rotation direction andthereafter rotating of the rotation device 1020 again in the secondrotation direction once again from t₅ to t₇. The processor 110 may emitX-rays to the subject by using the third light source 1035 among theplurality of light sources 1031, 1033 and 1035 during the rotation ofthe rotation device 1020 in the first rotation direction from t₅ to t₆.

The processor 110 may create at least one raw image of the subjectthrough the above operations and create a helical CT image of thesubject based on the at least one raw image.

FIG. 13 is a graph showing a CT method performed by the CT apparatus 100according to the second embodiment. Specifically, FIG. 13 is a graphshowing operational states of the plurality of light sources 1031, 1033and 1035, the rotation device 1020, and the transfer unit 1050 over timewhen the total number of the plurality of light sources 1031, 1033 and1035 is three.

The CT apparatus 100 according to various embodiments may obtain helicalCT images of a subject by an operating method shown in graphs 1300 andcreate a 3D image of the entire subject using the obtained helical CTimages. A description of parts of FIG. 13 that are the same as those ofFIG. 12 is omitted here.

According to various embodiments, operational states of the rotationdevice 1020, the first light source 1031, the second light source 1033,and the third light source 1035 from t₁ to t₇ are the same as the abovestates described with reference to FIG. 12. Referring to graphs of therotation device 1020, the first light source 1031, the second lightsource 1033, and the third light source 1035 among the graphs 1300, theprocessor 110 may control the rotation device 1020 to be repeatedlyrotated by a determined angle of rotation in a first rotation directionand thereafter rotated in a second rotation direction. The processor 110may emit X-rays to the subject using one of the plurality of lightsources 1031, 1033 and 1035 during the rotation of the rotation device1020 in the first rotation direction. For example, as shown in thegraphs 1300, the processor 110 may control the plurality of lightsources 1031, 1033 and 1035 to emit X-rays to the subject sequentiallyfrom the first light source 1031, the second light source 1033, and thethird light source 1035.

Referring to a graph of the transfer unit 1050 among the graphs 1300,the processor 110 according to various embodiments may control thetransfer unit 1050 to be moved constantly at a predetermined speed in apositive direction of an axis of rotation from t₁ to t₇. Some data ofhelical CT images of the subject may be lost when the transfer unit 1050is not stopped during the rotation of the rotation device 1020 in thesecond rotation direction, i.e., during restoration of the rotationdevice 1020 to an original position. To supplement the lost data, theprocessor 110 may move the transfer unit 1050 again at the predeterminedspeed in a negative direction of the axis of rotation. For example, theprocessor 110 may control the transfer unit 1050 to be moved constantlyat the predetermined speed in the negative direction of the axis ofrotation from t₇ to t₁₃.

Referring to graphs of the rotation device 1020, the first light source1031, the second light source 1033, and the third light source 1035among the graphs 1300, the processor 110 may control the rotation device1020 to be repeatedly rotated by a determined angle of rotation in thefirst rotation direction and thereafter rotated in the second rotationdirection from t₇ to t₁₃. The processor 110 may emit X-rays to thesubject using one of the plurality of light sources 1031, 1033 and 1035during the rotation of the rotation device 1020 in the first rotationdirection. For example, as shown in the graphs 1300, the processor 110may control the plurality of light sources 1031, 1033 and 1035 to emitX-rays to the subject sequentially from the third light source 1035, thesecond light source 1033 and the first light source 1031 from t₇ to t₁₃.

The processor 110 may create at least one raw image of the subjectthrough the above operations and create a helical CT image of thesubject based on the at least one raw image.

FIG. 14 is a flowchart 1400 of operations of the CT apparatus 100according to the second embodiment.

Referring to the flowchart 1400, in operation 1410, the processor 110 ofthe CT apparatus 100 according to various embodiments may rotate therotation device 1020 in a first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources 1031, 1033 and 1035.

In operation 1420, the processor 110 according to various embodimentsmay emit X-rays to a subject by using at least one of the plurality oflight sources 1031, 1033 and 1035 and detect X-rays passing through thesubject by one of the plurality of detectors 1041, 1043 and 1045 duringthe rotation of the rotation device 1020 in the first rotationdirection. The processor 110 may create at least one raw image of thesubject based on the X-rays detected using one of the plurality ofdetectors 1041, 1043 and 1045. The processor 110 may create a 3D imageof the subject using the at least one raw image of the subject.

In operation 1430, the processor 110 according to various embodimentsmay rotate the rotation device 1020 by the determined angle of rotationin the second rotation direction. The processor 110 according to variousembodiments may control all of the plurality of light sources 1031, 1033and 1035 not to emit X-rays to the subject during the rotation of therotation device 1020 by the determined angle of rotation in the secondrotation direction.

Third Embodiment

FIGS. 15A to 16 are diagrams for describing a CT apparatus 100 accordingto a third embodiment and a CT method using the same. A description ofparts of the third embodiment that are the same as those of the secondembodiment is omitted here.

FIG. 15A is a cross-sectional view of an x-y plane of a gantry of the CTapparatus 100 according to the third embodiment, and FIG. 15B is across-sectional view of a y-z plane of the gantry according to the thirdembodiment. In the CT apparatus 100 according to the third embodiment,positions of a plurality of light sources on a z-axis in the CTapparatus 100 according to the second embodiment are changed.

Referring to FIG. 15A, the CT apparatus 100 according to variousembodiments may include a gantry, a plurality of light sources 1531,1533 and 1535 and a plurality of detectors 1541, 1543 and 1545. Thegantry may include a ring-shaped rotation device 1520 rotatable about anaxis of rotation. The plurality of light sources 1531, 1533 and 1535 maybe arranged on the rotation device 1520 at regular intervals. Theplurality of detectors 1541, 1543 and 1545 may be arranged at positionsfacing and corresponding to the plurality of light sources 1531, 1533and 1535. The plurality of light sources 1531, 1533 and 1535 may emitX-rays to a subject loaded on a transfer unit 1550, and the plurality ofdetectors 1541, 1543 and 1545 may detect X-rays passing through thesubject. Although in this drawing, it is assumed for convenience ofdescription that a total number of the plurality of light sources isthree, the total number of the plurality of light sources is not limitedto three and may be two or greater than three.

According to various embodiments, the processor 110 may determine aninterval between angles of the plurality of light sources 1531, 1533 and1535 arranged in the rotation device 1520 and an angle of rotation ofthe rotation device 1520 based on the total number of the plurality oflight sources 1531, 1533 and 1535. The processor 110 may determine avalue obtained by dividing 360 degrees by the total number of theplurality of light sources 1531, 1533 and 1535 as an interval betweenangles of the plurality of light sources 1531, 1533 and 1535 arranged inthe rotation device 1520 and as an angle of rotation of the rotationdevice 1520.

When the plurality of detectors 1541, 1543 and 1545 according to variousembodiments are arranged at positions facing and corresponding to theplurality of light sources 1531, 1533 and 1535 and even when one of theplurality of light sources 1531, 1533 and 1535 emits X-rays to thesubject, the processor 110 may detect X-rays passing through the subjectby the detector 1541, 1543 or 1545 at a position corresponding to thelight source 1531, 1533 or 1535 emitting the X-rays. For example, X-rayspassing through the subject among X-rays emitted to the subject from thefirst light source 1531 may be detected by the first detector 1541arranged at the position corresponding to the first light source 1531,X-rays passing through the subject among X-rays emitted to the subjectfrom the second light source 1533 may be detected by the second detector1543 arranged at the position corresponding to the second light source1533, and X-rays passing through the subject among X-rays emitted to thesubject from the third light source 1535 may be detected by the thirddetector 1545 arranged at the position corresponding to the third lightsource 1535.

Referring to FIG. 15B, the plurality of light sources 1531, 1533 and1535 according to various embodiments may be arranged at positions on anaxis of rotation of the rotation device 1520 that are spaced a certaindistance from one another. For example, positions of the plurality oflight sources 1531, 1533 and 1535 on a z-axis may be different from oneanother. For example, the position of the first light source 1531 on thez-axis, the position of the second light source 1533 on the z-axis, andthe position of the third light source 1535 on the z-axis may bedifferent from one another. For example, the difference between thepositions of the first light source 1531 and the second light source1533 on the z-axis may be the same as the difference between thepositions of the second light source 1533 and the third light source1535 on the z-axis.

FIG. 16 is a graph showing a CT method performed by the CT apparatus 100according to the third embodiment. Specifically, FIG. 16 is a graphshowing operational states of the plurality of light sources 1531, 1533and 1535, the rotation device 1520, and the transfer unit 1550 over timewhen the total number of the plurality of light sources 1531, 1533 and1535 is three.

In the graph of the rotation device 1520 among the graphs 1600, anoperational state 1 may represent a state of rotation in a firstrotation direction, an operational state 0 may represent a state ofnon-rotation, and an operational state −1 may represent a state ofrotation in a second rotation direction opposite to the first rotationdirection. In the graphs of the first light source 1531, the secondlight source 1533, and the third light source 1535 among the graphs1600, an operational state 1 may represent a state in which X-rays areemitted, and an operational state 0 may represent a state in whichX-rays are not emitted. In the graph of the transfer unit 1550 among thegraphs 1600, an operational state 1 may represent a state of movement ina positive (+) direction of an axis of rotation, and an operationalstate −1 may represent a state of movement in a negative (−) directionof the axis of rotation.

The CT apparatus 100 according to various embodiments may obtain helicalCT images of a subject by an operation method shown in graphs 1600.

The processor 110 according to various embodiments may rotate therotation device 1520 in the first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources. For example, when the total number of the plurality of lightsources is three, it may be determined that the angle of rotation of therotation device 1520 is 120 degrees. Referring to the graph of therotation device 1520 among the graphs 1600, the processor 110 may rotatethe rotation device 1520 by 120 degrees in the first rotation directionfrom t₁ to t₂.

Referring to the graph of the transfer unit 1550 among the graphs 1600,the processor 110 according to various embodiments may move the transferunit 1550 at a predetermined speed in the direction of the axis ofrotation to obtain helical CT images of the subject from t₁ to t₂. Inthe CT apparatus 100 according to the third embodiment, the positions ofthe plurality of light sources 1531, 1533 and 1535 on the z-axis aredifferent from one another and thus helical CT images of the subject maybe obtained even when the transfer unit 1550 is moved during therotation of the rotation device 1520 in the first rotation direction.

The processor 110 according to various embodiments may emit X-rays tothe subject through at least one of the plurality of light sources 1531,1533 and 1535 during the rotation of the rotation device 1520 in thefirst rotation direction. For example, the processor 110 may control theplurality of light sources 1531, 1533 and 1535 to emit X-rays to thesubject from all of the plurality of light sources 1531, 1533 and 1535during the rotation of the rotation device 1520 in the first rotationdirection. For example, the processor 110 may control the plurality oflight sources 1531, 1533 and 1535 to alternately emit X-rays to thesubject in units of a unit angle in a predetermined order during therotation of the rotation device 1520 in the first rotation direction.

For example, referring to the graphs of the first light source 1531, thesecond light source 1533, and the third light source 1535 among thegraphs 1600, the processor 110 may emit X-rays to the subject using allof the first light source 1531, the second light source 1533, and thethird light source 1535 during the rotation of the rotation device 1520from 0 degrees to 120 degrees in the first rotation direction, i.e.,from t₁ to t₂.

For example, as shown in FIG. 7, the processor 110 may control theplurality of light sources 1531, 1533 and 1535 to emit X-rays to thesubject sequentially and alternately from the first light source 1531,the second light source 1533, and the third light source 1535. When itis assumed that emitting X-rays sequentially from the first light source1531, the second light source 1533, and the third light source 1535during the rotation of the rotation device 1520 by 1 degree in the firstrotation direction is one sequence, the processor 110 may repeatedlyperform the sequence 120 times at an interval of 1 degree to control theplurality of light sources 1531, 1533 and 1535 to alternately emitX-rays to the subject in the predetermined order during the rotation ofthe rotation device 1520 from 0 degrees to 120 degrees.

The processor 110 according to various embodiments may detect X-rayspassing through the subject through the plurality of detectors 1541,1543 and 1545 during the rotation of the rotation device 1520 in thefirst rotation direction. In this case, the processor 110 may create atleast one raw image of the subject based on the X-rays detected usingthe plurality of detectors 1541, 1543 and 1545. The processor 110 maycreate a 3D image of the subject based on the at least one raw image ofthe subject. In this case, the 3D image of the subject may be a helicalCT image.

The processor 110 according to various embodiments may rotate therotation device 1520 by a determined angle of rotation in the secondrotation direction. That is, the processor 110 may return the rotationdevice 1520 to an original position before the rotation of the rotationdevice 1520 in the first rotation direction. Referring to the graph ofthe rotation device 1520 among the graphs 1600, the processor 110 mayrotate the rotation device 1520 by 120 degrees in the second rotationdirection from t₂ to t₃.

Fourth Embodiment

FIGS. 17 to 21 are diagrams for describing a CT apparatus 100 accordingto a fourth embodiment and a CT method using the same.

FIG. 17 is a cross-sectional view of an x-y plane of a gantry of the CTapparatus 100 according to the fourth embodiment.

Referring to FIG. 17, the CT apparatus 100 according to variousembodiments may include a gantry, a plurality of light sources 1731,1733, 1735 and 1737, and a detector 1740. The gantry may include aring-shaped rotation device 1720 rotatable about an axis of rotation.The gantry may be divided into a first sub-device 1721 and a secondsub-device 1723 along a division line X. In this case, a subject may beeasily placed inside the gantry, because it is possible to combine thesecond sub-device 1723 with the first sub-device 1721 after the objectis placed inside the first sub-device 1721 of the rotation device 1720.Although for convenience of description, it is described above that therotation device 1720 is divided in half along the division line X, therotation device 1720 is not necessarily divided into the firstsub-device 1721 and the second sub-device 1723 along a 180-degree linepassing the center thereof and may be divided into various-sized parts.When the first sub-device 1721 and the second sub-device 1723 arecombined with each other, the first sub-device 1721 and the secondsub-device 1723 may be rotated together with the rotation of therotation device 1720.

The plurality of light sources 1731, 1733, 1735 and 1737 according tovarious embodiments may be spaced a certain distance from the firstsub-device 1721. The plurality of light sources 1731, 1733, 1735 and1737 may emit X-rays to a subject loaded on the transfer unit 1750.Although in this drawing, it is assumed for convenience of descriptionthat a total number of the plurality of light sources is four, the totalnumber of the plurality of light sources is not limited to four and maybe two or three or greater than four.

The detector 1740 according to various embodiments may be provided onthe second sub-device 1723. For example, when it is assumed that theplurality of light sources 1731, 1733, 1735 and 1737 are point lightsources, a cone beam angle of the plurality of light sources 1731, 1733,1735 and 1737 is about 30 degrees, and thus, the second sub-device 1723has a size occupying 210 degrees (180 degrees+30 degrees) of an entirecircumference of the rotation device 1720 with respect to the center ofthe rotation device 1720, and the detector 1740 may be configured toentirely surround inner sides of the second sub-device 1723.

According to various embodiments, the processor 110 may determine aninterval between angles of the plurality of light sources 1731, 1733,1735 and 1737 arranged in the first sub-device 1721 and an angle ofrotation of the rotation device 1720 based on the total number of theplurality of light sources 1731, 1733, 1735 and 1737. The processor 110may determine a value obtained by dividing 180 degrees by the totalnumber of the plurality of light sources 1731, 1733, 1735 and 1737 as aninterval between angles of the plurality of light sources 1731, 1733,1735 and 1737 arranged in the first sub-device 1721 and as the angle ofrotation of the rotation device 1720. For example, when the total numberof the plurality of light sources 1731, 1733, 1735 and 1737 is four, theplurality of light sources 1731, 1733, 1735 and 1737 may be arranged at45-degree intervals on the first sub-device 1721, and it may bedetermined that the angle of rotation of the rotation device 1720 is 45degrees.

When the detector 1740 according to various embodiments is configured toentirely surround the second sub-device 1723, the processor 110 iscapable of detecting X-rays passing through the subject by the detector1740 even when one of the plurality of light sources 1731, 1733, 1735and 1737 arranged in the first sub-device 1721 emits X-rays to thesubject.

FIG. 18 is a graph showing a CT method performed by the CT apparatus 100according to the fourth embodiment. Specifically, FIG. 18 is a graphshowing operational states of the plurality of light sources 1731, 1733,1735 and 1737, the rotation device 1720, and the transfer unit 1750 overtime when the total number of the plurality of light sources 1731, 1733,1735 and 1737 is four.

In the graph of the rotation device 1720 among the graphs 1800, anoperational state 1 may represent a state of rotation in a firstrotation direction, an operational state 0 may represent a state ofnon-rotation, and an operational state −1 may represent a state ofrotation in a second rotation direction opposite to the first rotationdirection. In the graphs of the first light source 1731, the secondlight source 1733, the third light source 1735, and the fourth lightsource 1737 among the graphs 1800, an operational state 1 may representa state in which X-rays are emitted and an operational state 0 mayrepresent a state in which X-rays are not emitted. In the graph of thetransfer unit 1750 among the graphs 1800, an operational state 1 mayrepresent a state of movement in a positive (+) direction of an axis ofrotation, and an operational state −1 may represent a state of movementin a negative (−) direction of the axis of rotation.

The CT apparatus 100 according to various embodiments may obtaincircular CT images of a subject by an operation method shown in thegraphs 1800.

The CT apparatus 100 according to various embodiments may obtaincircular CT images of a subject by an operation method shown in thegraphs 1800.

The processor 110 according to various embodiments may rotate therotation device 1720 in the first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources 1731, 1733, 1735 and 1737. For example, when the total number ofthe plurality of light sources 1731, 1733, 1735 and 1737 is four, theangle of rotation of the rotation device 1720 may be determined to be 45degrees. Referring to the graph of the rotation device 1720 among thegraphs 1800, the processor 110 may rotate the rotation device 1720 by 45degrees in the first rotation direction from t₁ to t₂.

Referring to the graph of the transfer unit 1750 among the graphs 1800,the processor 110 according to various embodiments may not move thetransfer unit 1750 to obtain a circular CT image of the subject.

The processor 110 according to various embodiments may emit X-rays tothe subject by using at least one of the plurality of light sources1731, 1733, 1735 and 1737 during the rotation of the rotation device1720 in the first rotation direction. For example, the processor 110 maycontrol the plurality of light sources 1731, 1733, 1735 and 1737 to emitX-rays to the subject from all of the plurality of light sources 1731,1733, 1735 and 1737 during the rotation of the rotation device 1720 inthe first rotation direction. The processor 110 may control theplurality of light sources 1731, 1733, 1735 and 1737 to repeatedlyperform a sequence of alternately emitting X-rays to the subject inunits of a unit angle from the plurality of light sources 1731, 1733,1735 and 1737 in a predetermined order during the rotation of therotation device 1720 in the first rotation direction.

For example, referring to the graphs of the first light source 1731, thesecond light source 1733, the third light source 1735, and the fourthlight source 1737 among the graphs 1800, the processor 110 may emitX-rays to the subject using all of the first light source 1731, thesecond light source 1733, the third light source 1735, and the fourthlight source 1737 during the rotation of the rotation device 1720 from 0degrees to 45 degrees, i.e., from t₁ to t₂, in the first rotationdirection.

For example, as shown in FIG. 7, the processor 110 may control theplurality of light sources 1731, 1733, 1735 and 1737 to repeatedlyperform a sequence of emitting X-rays to the subject in units of a unitangle alternately and sequentially from the plurality of light sources1731, 1733, 1735 and 1737.

The processor 110 according to various embodiments may detect X-rayspassing through the subject by the detector 1740 during the rotation ofthe rotation device 1720 in the first rotation direction. In this case,the processor 110 may create at least one raw image of the subject basedon the X-rays detected by the detector 1740. The processor 110 maycreate a 3D image of the subject based on the at least one raw image ofthe subject. In this case, the 3D image of the subject may be a circularCT image.

The processor 110 according to various embodiments may rotate therotation device 1720 by the determined angle of rotation in the secondrotation direction. That is, the processor 110 may return the rotationdevice 1720 to an original position before the rotation of the rotationdevice 1720 in the first rotation direction. Referring to the graph ofthe rotation device 1720 among the graphs 1800, the processor 110 mayrotate the rotation device 1720 by 45 degrees in the second rotationdirection from t₂ to t₃.

FIG. 19 is a graph showing a CT method performed by the CT apparatus 100according to the fourth embodiment. Specifically, FIG. 19 is a graphshowing operational states of the plurality of light sources 1731, 1733,1735 and 1737, the rotation device 1720, and the transfer unit 1750 overtime when the total number of the plurality of light sources 1731, 1733,1735 and 1737 is four.

The CT apparatus 100 according to various embodiments may obtain helicalCT images of a subject by an operation method shown in graphs 1900.

The processor 110 according to various embodiments may rotate therotation device 1720 in the first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources 1731, 1733, 1735 and 1737. For example, when the total number ofthe plurality of light sources 1731, 1733, 1735 and 1737 is four, it maybe determined that the angle of rotation of the rotation device 1720 is45 degrees. Referring to a graph of the rotation device 1720 among thegraphs 1900, the processor 110 may rotate the rotation device 1720 by 45degrees in the first rotation direction from t₁ to t₂.

The processor 110 according to various embodiments may control thetransfer unit 1750 to be moved by a predetermined distance in adirection of an axis of rotation for a predetermined time in response tothe start of the rotation of the rotation device 1720 in the firstrotation direction. Referring to a graph of the transfer unit 1750 amongthe graphs 1900, the processor 110 may control the transfer unit 1750 bythe predetermined distance in a positive direction of the axis ofrotation from t₁ to t₂.

The processor 110 according to various embodiments may emit X-rays tothe subject by using one of the plurality of light sources 1731, 1733,1735 and 1737 during the rotation of the rotation device 1720 in thefirst rotation direction. The processor 110 may emit X-rays to thesubject by using the first light source 1731 during the rotation of therotation device 1720 in the first rotation direction from t₁ to t₂. Inthis case, the second light source 1733, the third light source 1735,and the fourth light source 1737 may not emit X-rays. The detector 1740may detect X-rays passing through the subject during the emission of theX-rays from the first light source 1731. The processor 110 may create atleast one raw image of the subject based on the X-rays detected by thedetector 1740.

The processor 110 according to various embodiments may rotate therotation device 1720 in a second rotation direction opposite to thefirst rotation direction. The processor 110 may control the rotationdevice 1720 to be rotated by a determined angle of rotation in thesecond rotation direction after the rotation of the rotation device 1720by the determined angle of rotation in the first rotation direction.Referring to the graph of the rotation device 1720 among the graphs1900, the processor 110 may rotate the rotation device 1720 by 45degrees in the second rotation direction from t₂ to t₃. That is, theprocessor 110 may return the rotation device 1720 to an originalposition before the rotation of the rotation device 1720 in the firstrotation direction.

The processor 110 according to various embodiments may control thetransfer unit 1750 to not be moved, i.e., to be stopped, in response tothe start of the rotation of the rotation device 1720 in the secondrotation direction. Referring to the graph of the transfer unit 1750among the graphs 1900, the processor 110 may control the transfer unit1750 not to be moved from t₂ to t₃.

The processor 110 according to various embodiments may control all ofthe plurality of light sources 1731, 1733, 1735 and 1737 not to emitX-rays to the subject during the rotation of the rotation device 1720 inthe second rotation direction. Referring to the graphs of the firstlight source 1731, the second light source 1733, the third light source1735, and the fourth light source 1737 among the graphs 1900, theprocessor 110 may control all of the first light source 1731, the secondlight source 1733 and the third light source 1735 not to emit X-raysfrom t₂ to t₃.

The processor 110 according to various embodiments may repeatedlyperform rotating of the rotation device 1720 by the determined angle ofrotation in the first rotation direction and rotating of the rotationdevice 1720 by the determined angle of rotation in the second rotationdirection a number of times corresponding to the total number of theplurality of light sources.

The processor 110 according to various embodiments may rotate therotation device 1720 again by the determined angle of rotation in thefirst rotation direction. Referring to the graph of the rotation device1720 among the graphs, the processor 110 may rotate the rotation device1720 again by 45 degrees in the first rotation direction from t₃ to t₄.

The processor 110 according to various embodiments may control thetransfer unit 1750 to be moved by a predetermined distance in adirection of an axis of rotation for a predetermined time in response tothe start of the rotation of the rotation device 1720 again in the firstrotation direction. Referring to the graph of the transfer unit 1750among the graphs 1900, the processor 110 may control the transfer unit1750 to be moved by a predetermined distance in a positive direction ofthe axis of rotation from t₃ to t₄.

The processor 110 according to various embodiments may emit X-rays tothe subject by using one of the plurality of light sources 1731, 1733,1735 and 1737 during the rotation of the rotation device 1720 in thefirst rotation direction. The processor 110 may emit X-rays to thesubject using the second light source 1733 during the rotation of therotation device 1720 in the first rotation direction from t₃ to t₄. Forexample, the second light source 1733 may be the light source closest tothe first light source 1731 in the first rotation direction. In thiscase, the first light source 1731, the third light source 1735 and thefourth light source 1737 may not emit X-rays. The detector 1740 maydetect X-rays passing through the subject during the emission of theX-rays from the second light source 1733. The processor 110 may createat least one raw image of the subject based on the X-rays detected bythe detector 1740.

The processor 110 according to various embodiments may rotate therotation device 1720 again in the second rotation direction opposite tothe first rotation direction. Referring to the graph of the rotationdevice 1720 among the graphs 1900, the processor 110 may rotate therotation device 1720 again by 45 degrees in the second rotationdirection from t₄ to t₅.

The processor 110 according to various embodiments may control thetransfer unit 1750 to not be moved, i.e., to be stopped, in response tothe start of the rotation of the rotation device 1720 again in thesecond rotation direction. Referring to the graph of the transfer unit1750 among the graphs 1900, the processor 110 may control the transferunit 1750 not to be moved from t₄ to t₅.

The processor 110 according to various embodiments may control all ofthe plurality of light sources 1731, 1733, 1735 and 1737 not to emitX-rays to the subject during the rotation of the rotation device 1720again in the second rotation direction. Referring to the graphs of thefirst light source 1731, the second light source 1733, the third lightsource 1735, and the fourth light source 1737, the processor 110 maycontrol all of the first light source 1731, the second light source1733, the third light source 1735, and the fourth light source 1737 notto emit X-rays from t₄ to t₅.

The processor 110 according to various embodiments may repeatedlyperform rotating of the rotation device 1720 in the first rotationdirection and rotating of the rotation device 1720 in the secondrotation direction two times from t₅ to t₉. The processor 110 may emitX-rays to the subject using the third light source 1735 among theplurality of light sources during the rotation of the rotation device1720 in the first rotation direction from t₅ to t₆. The processor 110may emit X-rays to the subject using the fourth light source 1737 amongthe plurality of light sources during the rotation of the rotationdevice 1720 in the first rotation direction from t₇ to t₈.

The processor 110 may create at least one raw image of the subjectthrough the above operations and create a helical CT image of thesubject based on the at least one raw image.

FIG. 20 is a graph showing a CT method performed by the CT apparatus 100according to the fourth embodiment. Specifically, FIG. 20 is a graphshowing operational states of the plurality of light sources 1731, 1733,1735 and 1737, the rotation device 1720, and the transfer unit 1750 overtime when the total number of the plurality of light sources 1731, 1733,1735 and 1737 is four.

The CT apparatus 100 according to various embodiments may obtain helicalCT images of a subject by an operating method shown in graphs 1300 andcreate a 3D image of the entire subject using the obtained helical CTimages. A description of parts of FIG. 20 that are the same as those ofFIG. 19 is omitted here.

According to various embodiments, operational states of the rotationdevice 1720, the first light source 1731, the second light source 1733,the third light source 1735, and the fourth light source 1737 from t₁ tot₉ are the same as the above states described with reference to FIG. 19.Referring to graphs of the rotation device 1720, the first light source1731, the second light source 1733, the third light source 1735 and thefourth light source 1737 among the graphs 2000, the processor 110 maycontrol the rotation device 1720 to be repeatedly rotated by adetermined angle of rotation in a first rotation direction andthereafter rotated in a second rotation direction. The processor 110 mayemit X-rays to the subject using one of the plurality of light sources1731, 1733, 1735 and 1737 during the rotation of the rotation device1720 in the first rotation direction. For example, as shown in thegraphs 2000, the processor 110 may control the plurality of lightsources 1731, 1733, 1735 and 1737 to emit X-rays to the subjectsequentially from the first light source 1731, the second light source1733, the third light source 1735, and the fourth light source 1737.

According to various embodiments, referring to the graph of the transferunit 1750 among the graphs 2000, the processor 110 may control thetransfer unit 1750 to be moved constantly at a predetermined speed in apositive direction of an axis of rotation from t₁ to t₉. Some data ofhelical CT images of the subject may be lost when the transfer unit 1750is not stopped during the rotation of the rotation device 1720 in thesecond rotation direction, i.e., during restoration of the rotationdevice 1720 to an original position. To supplement the lost data, theprocessor 110 may move the transfer unit 1750 again at the predeterminedspeed in a negative direction of the axis of rotation. For example, theprocessor 110 may control the transfer unit 1750 to be moved constantlyat a predetermined speed in the negative direction of the axis ofrotation from t₉ to t₁₇.

Referring to the graphs of the rotation device 1720, the first lightsource 1731, the second light source 1733, the third light source 1735,and the fourth light source 1737 among the graphs 2000, the processor110 may control the rotation device 1720 to be repeatedly rotated by adetermined angle of rotation in the first rotation direction andthereafter rotated in the second rotation direction from t₉ to t₁₇. Theprocessor 110 may emit X-rays to the subject using one of the pluralityof light sources 1731, 1733, 1735 and 1737 during the rotation of therotation device 1720 in the first rotation direction. For example, asshown in the graphs 2000, the processor 110 may control the plurality oflight sources 1731, 1733, 1735 and 1737 to emit X-rays to the subjectsequentially from the fourth light source 1737, the third light source1735, the second light source 1733, and the first light source 1731 fromt₉ to t₁₇.

The processor 110 may create at least one raw image of the subjectthrough the above operations and create a helical CT image of thesubject based on the at least one raw image.

FIG. 21 is a flowchart 2100 of operations of the CT apparatus 100according to the fourth embodiment.

Referring to the flowchart 2100, in operation 2110, the processor 110 ofthe CT apparatus 100 according to various embodiments may rotate therotation device 1720 in a first rotation direction by an angle ofrotation determined based on the total number of the plurality of lightsources 1731, 1733, 1735 and 1737.

In operation 2120, the processor 110 according to various embodimentsmay emit X-rays to a subject by using at least one of the plurality oflight sources 1731, 1733, 1735 and 1737 during the rotation of therotation device 1720 in the first rotation direction.

In operation 2130, the processor 110 according to various embodimentsmay detect X-rays passing through the subject by the detector 1740during the rotation of the rotation device 1720 in the first rotationdirection. The processor 110 may create at least one raw image of thesubject based on the X-rays detected by the detector 1740. The processor110 may create a 3D image of the subject using the at least one rawimage of the subject.

In operation 2140, the processor 110 according to various embodimentsmay rotate the rotation device 1720 by the determined angle of rotationin a second rotation direction. The processor 110 according to variousembodiments may control all of the plurality of light sources 1731,1733, 1735 and 1737 not to emit X-rays to the subject during therotation of the rotation device 1720 by the determined angle of rotationin the second rotation direction.

Fifth Embodiment

FIGS. 22 to 26 are diagrams for describing a CT apparatus 100 accordingto a fifth embodiment and a CT method using the same. A description ofparts of the fifth embodiment that are the same as those of the otherembodiments is omitted here.

FIG. 22 is a cross-sectional view of an x-y plane of a gantry of the CTapparatus 100 according to the fifth embodiment.

Referring to FIG. 22, the CT apparatus 100 according to variousembodiments may include a gantry, a plurality of light sources 2231,2233 and 2235 and a detector 2240. The gantry may include a firstrotation device 2221 and a second rotation device 2223 that have a ringshape, share an axis of rotation, and are rotatable independently ofeach other. The plurality of light sources 2231, 2233 and 2235 may bearranged on the first rotation device 2221 at regular intervals. Theplurality of light sources 2231, 2233, and 2235 may emit X-rays to asubject loaded on a transfer unit 2250. Although in this drawing, it isassumed for convenience of description that a total number of theplurality of light sources 2231, 2233 and 2235 is three, the totalnumber of the plurality of light sources 2231, 2233 and 2235 is notlimited to three and may be two or greater than three.

The detector 2240 according to various embodiments may be disposed inone area of the second rotation device 2223 and detect X-rays passingthrough the subject. An initial position of the second rotation device2223 may be set to a position facing and corresponding to a light sourceset to first emit X-rays among the plurality of light sources 2231, 2233and 2235. For example, when the first light source 2231 among theplurality of light sources 2231, 2233 and 2235 is set to first emitX-rays at an initial stage, the processor 110 may set a position atwhich the detector 2240 faces and corresponds to the first light source2231 to an initial position of the second rotation device 2223.

FIG. 23 is a graph showing a CT method performed by the CT apparatus 100according to the fifth embodiment. Specifically, FIG. 23 is a graphshowing operational states of the plurality of light sources 2231, 2233and 2235, the first rotation device 2221, the second rotation device2223, and the transfer unit 2250 over time when the total number of theplurality of light sources 2231, 2233 and 2235 is three.

In the graphs of the first rotation device 2221 and the second rotationdevice 2223 among graphs 2300, an operational state 1 may represent astate of rotation in a first rotation direction, an operational state 0may represent a state of non-rotation, and an operational state −1 mayrepresent a state of rotation in a second rotation direction opposite tothe first rotation direction. In the graphs of the first light source2231, the second light source 2233, and the third light source 2235among the graphs 2300, an operational state 1 may represent a state inwhich X-rays are emitted and an operational state 0 may represent astate in which X-rays are not emitted. In the graph of the transfer unit2250 among the graphs 2300, an operational state 1 may represent a stateof movement in a positive (+) direction of an axis of rotation, and anoperational state −1 may represent a state of movement in a negative (−)direction of the axis of rotation.

The CT apparatus 100 according to various embodiments may obtaincircular CT images of a subject by an operation method shown in thegraphs 2300.

The processor 110 according to various embodiments may control the firstrotation device 2221 to repeatedly perform a first operation of beingrotated in the first rotation direction by an angle of rotationdetermined based on the total number of the plurality of light sources2231, 2233 and 2235 and a second operation of being rotated by thedetermined angle of rotation in the second rotation direction. Forexample, when the total number of the plurality of light sources 2231,2233 and 2235 is three, the processor 110 may determine the angle ofrotation of the first rotation device 2221 to be 120 degrees. Theprocessor 110 may determine a number of times the first operation andthe second operation are repeatedly performed by the first rotationdevice 2221 based on the total number of the plurality of light sources.For example, when the total number of the plurality of light sources2231, 2233 and 2235 is three, the processor 110 may determine the numberof times the first operation and the second operation are repeatedlyperformed by the first rotation device 2221 to be three.

Referring to the graph of the transfer unit 2250 among the graphs 2300,the processor 110 according to various embodiments may not move thetransfer unit 2250 to obtain a circular CT image of the subject.

The processor 110 according to various embodiments may control thesecond rotation device 2223 to be rotated in the first rotationdirection at the same speed of rotation as the first rotation device2221 while the first and second operations are repeatedly performed bythe first rotation device 2221. Referring to the graph of the secondrotation device 2223 among the graphs 2300, the second rotation device2223 may be rotated in the first rotation direction from t₁ to t₇. Forexample, the processor 110 may rotate the second rotation device 2223 inthe first rotation direction at the same speed of rotation as the firstrotation device 2221.

The processor 110 according to various embodiments may emit X-rays tothe subject by using at least one of the plurality of light sources2231, 2233 and 2235 during the rotation of the first rotation device2221 in the first rotation direction. The processor 110 may emit X-raysto the subject using the first light source 2231 during the rotation ofthe first light source 2231 in the first rotation direction from t₁ tot₂. In this case, the second light source 2233 and the third lightsource 2235 may not emit X-rays. The processor 110 may detect X-rayspassing through the subject using the detector 2240 disposed at aposition facing and corresponding to the first light source 2231 duringthe emission of the X-rays from the first light source 2231. Theprocessor 110 may create at least one raw image of the subject based onthe X-rays detected by the detector 2240. As described above, theprocessor 110 may emit X-rays to the subject using the second lightsource 2233 from t₃ to t₄ and emit X-rays to the subject using the thirdlight source 2235 from t₅ to t₆.

The processor 110 according to various embodiments may rotate the firstrotation device 2221 in the second rotation direction. The processor 110may control the first rotation device 2221 to be rotated by a determinedangle of rotation in the second rotation direction after the rotation ofthe first rotation device 2221 by the determined angle of rotation inthe first rotation direction. Referring to the graph of the firstrotation device 2221 among the graphs 2300, the processor 110 may rotatethe first rotation device 2221 by 120 degrees in the second rotationdirection from t₂ to t₃. That is, the processor 110 may return the firstrotation device 2221 to an original position before the rotation of thefirst rotation device 2221 in the first rotation direction. As describedabove, the processor 110 may rotate the first rotation device 2221 by120 degrees in the second rotation direction from t₄ to t₅ and rotatethe first rotation device 2221 by 120 degrees in the second rotationdirection from t₆ to t₇.

The processor 110 may create at least one raw image of the subjectthrough the above operations and create a circular CT image of thesubject based on the at least one raw image.

FIG. 24 is a graph showing a CT method performed by the CT apparatus 100according to the fifth embodiment. Specifically, FIG. 24 is a graphshowing operational states of the plurality of light sources 2231, 2233and 2235, the first rotation device 2221, the second rotation device2223, and the transfer unit 2250 over time when the total number of theplurality of light sources 2231, 2233 and 2235 is three.

The CT apparatus 100 according to various embodiments may obtain helicalCT images of a subject by an operating method shown in graphs 2400 andcreate a 3D image of the entire subject using the obtained helical CTimages. A description of parts of FIG. 24 that are the same as those ofFIG. 23 is omitted here.

According to an embodiment, operational states of the first rotationdevice 2221, the second rotation device 2223, the first light source2231, the second light source 2233, and the third light source 2235 fromt₁ to t₇ are the same as the above states described with reference toFIG. 23. Referring to graphs of the first rotation device 2221, thesecond rotation device 2223, the first light source 2231, the secondlight source 2233, and the third light source 2235 among the graphs2400, the processor 110 may control the first rotation device 2221 to berepeatedly rotated by a determined angle of rotation in a first rotationdirection and thereafter rotated in a second rotation direction. Theprocessor 110 may control the second rotation device 2223 to be rotatedat the same speed of rotation as the first rotation device 2221 whilethe first rotation device 2221 repeatedly performs the above operations.The processor 110 according to various embodiments may emit X-rays tothe subject by using one of the plurality of light sources 2231, 2233and 2235 during the rotation of the first rotation device 2221 in thefirst rotation direction. For example, as shown in the graphs 2400, theprocessor 110 may control the plurality of light sources 2231, 2233 and2235 to emit X-rays to the subject sequentially from the first lightsource 2231, the second light source 2233, and the third light source2235.

The processor 110 according to various embodiments may control thetransfer unit 2250 to be moved by a predetermined distance in a positivedirection of an axis of rotation during the rotation of the firstrotation device 2221 in the first rotation direction. Referring to thegraph of the transfer unit 2250 among the graphs 2400, the processor 110may move the transfer unit 2250 by the predetermined distance from t₁ tot₂, from t₃ to t₄, and from t₅ to t₆.

The processor 110 may create at least one raw image of the subjectthrough the above operations and create a helical CT image of thesubject based on the at least one raw image. When the method shown inthe graphs 2400 is used, the transfer unit 2250 is moved only duringemission of X-rays by using one of the plurality of light sources 2231,2233 and 2235 and thus helical CT images of the subject may be obtained.

FIG. 25 is a graph showing a CT method performed by the CT apparatus 100according to the fifth embodiment. Specifically, FIG. 25 is a graphshowing operational states of the plurality of light sources 2231, 2233and 2235, the first rotation device 2221, the second rotation device2223, and the transfer unit 2250 over time when the total number of theplurality of light sources 2231, 2233 and 2235 is three.

The CT apparatus 100 according to various embodiments may obtain helicalCT images of a subject by an operating method shown in graphs 2500 andcreate a 3D image of the entire subject using the obtained helical CTimages. A description of parts of FIG. 25 that are the same as those ofFIG. 24 is omitted here.

According to various embodiments, operational states of the firstrotation device 2221, the second rotation device 2223, the first lightsource 2231, the second light source 2233, and the third light source2235 from t₁ to t₇ are the same as the above states described withreference to FIG. 24. Referring to the graphs of the first rotationdevice 2221, the second rotation device 2223, the first light source2231, the second light source 2233, and the third light source 2235among the graphs 2500, the processor 110 may control the first rotationdevice 2221 to be repeatedly rotated by a determined angle of rotationin a first rotation direction and thereafter rotated in a secondrotation direction. The processor 110 may emit X-rays to the subjectusing one of the plurality of light sources 2231, 2233 and 2235 duringthe rotation of the first rotation device 2221 in the first rotationdirection. For example, as shown in the graphs 2500, the processor 110may control the plurality of light sources 2231, 2233 and 2235 to emitX-rays to the subject sequentially from the first light source 2231, thesecond light source 2233, and the third light source 2235.

The processor 110 according to various embodiments may control thesecond rotation device 2223 to be rotated at the same speed of rotationas the first rotation device 2221 in the first rotation direction whilethe first rotation device 2221 is repeatedly rotated by the determinedangle of rotation in the first rotation direction and thereafter rotatedin the second rotation direction. Referring to the graph of the secondrotation device 2223 among the graphs 2500, the processor 110 may rotatethe second rotation device 2223 in the first rotation direction from t₁to t₁₃.

According to various embodiments, referring to the graph of the transferunit 2250 among the graphs 2500, the processor 110 may control thetransfer unit 2250 to be moved constantly at a predetermined speed in apositive direction of an axis of rotation from t₁ to t₇. Some data ofhelical CT images of the subject may be lost when the transfer unit 2250is not stopped during the rotation of the first rotation device 2221 inthe second rotation direction, i.e., during restoration of the firstrotation device 2221 to an original position. To supplement the lostdata, the processor 110 may move the transfer unit 2250 again at thepredetermined speed in a negative direction of the axis of rotation. Forexample, the processor 110 may move the transfer unit 2250 to be movedconstantly at the predetermined speed in the negative direction of theaxis of rotation from t₇ to t₁₃.

Referring to the graphs of the first rotation device 2221, the secondrotation device 2223, the first light source 2231, the second lightsource 2233, and the third light source 2235 among the graphs 2500, theprocessor 110 may control the first rotation device 2221 to berepeatedly rotated by the determined angle of rotation in the firstrotation direction and thereafter rotated in the second rotationdirection from t₇ to t₁₃. The processor 110 may emit X-rays to thesubject using one of the plurality of light sources 2231, 2233 and 2235during the rotation of the first rotation device 2221 in the firstrotation direction. For example, as shown in the graphs 2500, theprocessor 110 may control the plurality of light sources 2231, 2233 and2235 to emit X-rays to the subject sequentially from the third lightsource 2235, the second light source 2233, and the first light source2231 from t₇ to t₁₃.

The processor 110 may create at least one raw image of the subjectthrough the above operations and create a helical CT image of thesubject based on the at least one raw image.

FIG. 26 is a flowchart 2600 of operations of the CT apparatus 100according to the fifth embodiment.

Referring to the flowchart 2600, in operation 2610, the processor 110 ofthe CT apparatus 100 according to various embodiments may control thefirst rotation device 2221 to repeatedly perform a first operation ofbeing rotated in the first rotation direction by an angle of rotationdetermined based on the total number of the plurality of light sources2231, 2233 and 2235 and a second operation of being rotated by thedetermined angle of rotation in the second rotation direction. Theprocessor 110 may determine a number of times the first operation andthe second operation are repeatedly performed by the first rotationdevice 2221, for example, based on the total number of the plurality oflight sources 2231, 2233 and 2235.

In operation 2620, the processor 110 according to various embodimentsmay control the second rotation device 2223 to be rotated in the firstrotation direction at the same speed of rotation as the first rotationdevice 2221 while the first and second operations are repeatedlyperformed by the first rotation device 2221.

In operation 2630, the processor 110 according to various embodimentsmay emit X-rays to a subject by using one of the plurality of lightsources 2231, 2233 and 2235 and detect X-rays passing through thesubject by the detector 2240 during the performance of the firstoperation by the first rotation device 2221. The processor 110 maycreate at least one raw image of the subject based on the X-raysdetected by the detector 2240. The processor 110 may create a 3D imageof the subject using the at least one raw image of the subject.

Sixth Embodiment

FIGS. 27A to 30 are diagrams for describing a CT apparatus 100 accordingto a sixth embodiment and a CT method using the same. A description ofparts of the fifth embodiment that are the same as those of the otherembodiments is omitted here.

FIG. 27A is a cross-sectional view of an x-y plane of a gantry of the CTapparatus 100 according to the sixth embodiment, and FIG. 27B is across-sectional view of a y-z plane of the gantry according to the sixthembodiment.

Referring to FIG. 27A, the CT apparatus 100 according to variousembodiments may include a gantry, a plurality of first light sources2731, 2732 and 2733, a plurality of second light sources 2734, 2735 and2736, and a detector 2740. The gantry may include a first rotationdevice 2721, a second rotation device 2723 and a third rotation device2725 that have a ring shape, share an axis of rotation, and arerotatable independently of one another. The plurality of first lightsources 2731, 2732 and 2733 may be arranged on the first rotation device2721 at regular intervals. The plurality of second light sources 2734,2735 and 2736 may be arranged on the second rotation device 2723 atregular intervals. The plurality of first light sources 2731, 2732 and2733 and the plurality of second light sources 2734, 2735 and 2736 mayemit X-rays to a subject loaded on the transfer unit 2750. In thisdrawing, it is assumed for convenience of description that the totalnumber of the plurality of first light sources is three and the totalnumber of the plurality of second light sources is three, but the lightsources are not limited thereto.

The detector 2740 according to various embodiments may be provided inone area of the third rotation device 2725 and detect X-rays passingthrough the subject. An initial position of the third rotation device2725 may be set to a position at which the detector 2740 may face andcorrespond to a light source set to first emit X-rays among theplurality of first light sources 2731, 2732 and 2733 and the pluralityof second light sources 2734, 2735 and 2736. For example, when the firstlight source 2731 is set to first emit X-rays at an initial stage, theprocessor 110 may set a position at which the detector 2740 may face andcorrespond to the first light source 2731 to an initial position of thethird rotation device 2725.

Referring to FIG. 27B, a layout plan of the first rotation device 2721,a layout plan of the second rotation device 2723, and a layout plan ofthe third rotation device 2725 may be provided to be parallel to oneanother. For example, positions of the plurality of first light sources2731, 2732 and 2733 on a z-axis may be different from those of theplurality of second light sources 2734, 2735 and 2736 on the z-axis. Forexample, the positions of the first light source 2731, the second lightsource 2732, and the third light source 2733 on the z-axis may bedifferent from those of the second light source 2734, the b^(th) lightsource 2735, and the c^(th) light source 2736 on the z-axis.

FIG. 28 is a graph showing a CT method performed by the CT apparatus 100according to the sixth embodiment. Specifically, FIG. 28 is a graphshowing operational states of the plurality of first light sources 2731,2732 and 2733, the plurality of second light sources 2734, 2735 and2736, the first rotation device 2721, the second rotation device 2723,the third rotation device 2725, and the transfer unit 2750 over timewhen the total number of the plurality of first light sources 2731, 2732and 2733 and the total number of the plurality of second light sources2734, 2735 and 2736 are each three.

In the graphs of the first rotation device 2721, the second rotationdevice 2723 and the third rotation device 2725 among the graphs 2800, anoperational state 1 may represent a state of rotation in a firstrotation direction, an operational state 0 may represent a state ofnon-rotation, and an operational state −1 may represent a state ofrotation in a second rotation direction opposite to the first rotationdirection. In the graphs of the first light source 2731, the secondlight source 2732, the third light source 2733, the second light source2734, the b^(th) light source 2735, and the c^(th) light source 2736among the graphs 2800, an operational state 1 may represent a state inwhich X-rays are emitted and an operational state 0 may represent astate in which X-rays are not emitted. In the graph of the transfer unit2750 among the graphs 2800, an operational state 1 may represent a stateof movement in a positive (+) direction of an axis of rotation, and anoperational state −1 may represent a state of movement in a negative (−)direction of the axis of rotation.

The CT apparatus 100 according to various embodiments may obtaincircular CT images of a subject by an operation method shown in thegraphs 2800.

According to various embodiments, the processor 110 may control thefirst rotation device 2721 to repeatedly perform a first operation ofbeing rotated in the first direction by an angle of rotation determinedby the total number of the plurality of first light sources 2731, 2732and 2733 and the total number of the plurality of second light sources2734, 2735 and 2736 and a second operation of being rotated by thedetermined angle of rotation in the second rotation direction. Theprocessor 110 may determine a value obtained by dividing 360 degrees bythe total number of the plurality of first light sources 2731, 2732 and2733 and the total number of the plurality of second light sources 2734,2735 and 2736 as an angle of rotation of the first rotation device 2721,For example, when the total number of the plurality of first lightsources 2731, 2732 and 2733 and the total number of the second lightsources 2734, 2735 and 2736 are each three, the processor 110 maydetermine an angle of rotation of the first rotation device 2721 to be60 degrees.

According to various embodiments, the processor 110 may determine anumber of times the first operation and the second operation arerepeatedly performed by the first rotation device 2721 based on thetotal number of the plurality of first light sources 2731, 2732 and 2733and the total number of the plurality of second light sources 2734, 2735and 2736. For example, when the total number of the plurality of firstlight sources 2731, 2732 and 2733 and the total number of the pluralityof second light sources 2734, 2735 and 2736 are each three, theprocessor 110 may determine a number of times the first operation andthe second operation are repeatedly performed by the first rotationdevice 2721 to be three.

The processor 110 according to various embodiments may control thesecond rotation device 2723 to repeatedly perform a third operation ofbeing rotated by the determined angle of rotation in the second rotationdirection and a fourth operation of being rotated by the determinedangle of rotation in the first rotation direction. The processor 110 maycontrol the second rotation device 2723 to be rotated at the same speedof rotation as the first rotation device 2721.

According to various embodiments, the first operation of the firstrotation device 2721 and the third operation of the second rotationdevice 2723 may be performed simultaneously, and the second operation ofthe first rotation device 2721 and the fourth operation of the secondrotation device 2723 may be performed simultaneously. That is, the firstrotation device 2721 and the second rotation device 2723 may be rotatedin different directions. For example, the processor 110 may rotate thesecond rotation device 2723 in the second rotation direction during therotation of the first rotation device 2721 in the first rotationdirection and rotate the second rotation device 2723 in the firstrotation direction during the rotation of the first rotation device 2721in the second rotation direction.

The processor 110 according to various embodiments may control the thirdrotation device 2725 to be rotated in the first rotation direction atthe same speed of rotation as the first rotation device 2721 and thesecond rotation device 2723 while the first rotation device 2721repeatedly performs the first operation and the second operation and thesecond rotation device 2723 repeatedly performs the third operation andthe fourth operation. For example, at t₁, the detector 2740 may bearranged at a position on the third rotation device 2725 to face andcorrespond to the first light source 2731, and from t₁ to t₇, the thirdrotation device 2725 may be rotated in the first rotation direction atthe same speed of rotation as the first rotation device 2721 and thesecond rotation device 2723. In this case, even when X-rays are emittedin an order of the first light source 2731, the second light source2734, the second light source 2732, the b^(th) light source 2735, thethird light source 2733, and the c^(th) light source 2736, the detector2740 may be always located at a position facing a light source emittingX-rays. Accordingly, the detector 2740 may detect X-rays passing throughthe subject from t₁ to t₇.

Referring to the graph of the transfer unit 2750 among the graphs 2800,the processor 110 according to various embodiments may not move thetransfer unit 2750 to obtain a circular CT image of the subject.

The processor 110 according to various embodiments may emit X-rays tothe subject by using one of the plurality of first light sources 2731,2732 and 2733 during the rotation of the first rotation device 2721 inthe first rotation direction, i.e., the performance of the firstoperation by the first rotation device 2721. The processor 110 may emitX-rays to the subject using the first light source 2731 during therotation of the first rotation device 2721 in the first rotationdirection from t₁ to t₂. In this case, neither the second light source2732 and the third light source 2733 nor the plurality of second lightsources 2734, 2735 and 2736 may emit X-rays. The processor 110 maydetect X-rays passing through the subject using the detector 2740 duringthe emission of the X-rays from the first light source 2731. Theprocessor 110 may create at least one raw image of the subject based onthe X-rays detected by the detector 2740. As described above, theprocessor 110 may emit X-rays to the subject only using the second lightsource 2732 from t₃ to t₄ and emit X-rays to the subject only using thethird light source 2733 from t₅ to t₆.

The processor 110 according to various embodiments may emit X-rays tothe subject using one of the plurality of second light sources 2734,2735 and 2736 during the rotation of the second rotation device 2723 inthe first rotation direction, i.e., the performance of the fifthoperation by the second rotation device 2723. The processor 110 may emitX-rays to the subject using the second light source 2734 during therotation of the second rotation device 2723 from t₂ to t₃. In this case,neither the b^(th) light source 2735 and the c^(th) light source 2736nor the plurality of first light sources 2731, 2732 and 2733 may emitX-rays. The processor 110 may detect X-rays passing through the subjectusing the detector 2740 during the emission of the X-rays from thea^(th) light source 2734. The processor 110 may create at least one rawimage of the subject based on the X-rays detected by the detector 2740.As described above, the processor 110 may emit X-rays to the subjectonly using the b^(th) light source 2735 from t₄ to t₅, and emit X-raysto the subject only using the c^(th) light source 2736 from t₆ to t₇.

The processor 110 may create at least one raw image of the subjectthrough the above operations and create a circular CT image of thesubject based on the at least one raw image. When the method shown inthe graphs 2800 is used, the second rotation device 2723 may be rotatedin the first rotation direction to emit X-rays using the plurality ofsecond light sources 2734, 2735 and 2736 during the rotation of thefirst rotation device 2721 in the second rotation direction, i.e.,restoration of the first rotation device 2721 to an original positionbefore the rotation in the first rotation direction.

FIG. 29 is a graph showing a CT method performed by the CT apparatus 100according to the sixth embodiment. Specifically, FIG. 29 is a graphshowing operational states of the plurality of first light sources 2731,2732 and 2733, the plurality of second light sources 2734, 2735 and2736, the first rotation device 2721, the second rotation device 2723,the third rotation device 2725, and the transfer unit 2750 over time.

The CT apparatus 100 according to various embodiments may obtain helicalCT images of a subject by an operating method shown in graphs 2900 andcreate a 3D image of the entire subject using the obtained helical CTimages. A description of parts of FIG. 29 that are the same as those ofFIG. 28 is omitted here.

According to various embodiments, operational states of the firstrotation device 2721, the second rotation device 2723, the thirdrotation device 2725, the first light source 2731, the second lightsource 2732, the third light source 2733, the second light source 2734,the b^(th) light source 2735, and the c^(th) light source 2736 from t₁to t₇ are the same as the above states described with reference to FIG.28. Referring to the graphs of the first rotation device 2721, thesecond rotation device 2723, the third rotation device 2725, the firstlight source 2731, the second light source 2732, the third light source2733, the second light source 2734, the b^(th) light source 2735, andthe c^(th) light source 2736 among the graphs 2900, the processor 110may control the first rotation device 2721 to be repeatedly rotated by adetermined angle of rotation in a first rotation direction and rotatedin a second rotation direction. The processor 110 may control the secondrotation device 2723 to be repeatedly rotated by the determined angle ofrotation in the second rotation direction at the same speed of rotationas the first rotation device 2721 and rotated in the first rotationdirection while the first rotation device 2721 repeatedly performs theabove operations.

According to various embodiments, the processor 110 may emit X-rays tothe subject using one of the plurality of first light sources 2731, 2732and 2733 during the rotation of the first rotation device 2721 in thefirst rotation direction, and emit X-rays to the subject using one ofthe plurality of second light sources 2734, 2735 and 2736 during therotation of the second rotation device 2723 in the first rotationdirection. For example, as shown in the graphs 2900, the processor 110may control the plurality of first light sources 2731, 2732 and 2733 andthe plurality of second light sources 2734, 2735 and 2736 to emit X-raysto the subject in the order of the first light source 2731, the a t_(h)light source 2734, the second light source 2732, the b^(th) light source2735, the third light source 2733, and the c^(th) light source 2736.

The processor 110 according to various embodiments may control thetransfer unit 2750 to be moved at a predetermined speed in a positivedirection of an axis of rotation during the rotation of the firstrotation device 2721 and the second rotation device 2723. Referring tothe graph of the transfer unit 2750 among the graphs 2900, the processor110 may move the transfer unit 2750 at the predetermined speed from t₁to t₇.

The processor 110 may create at least one raw image of the subjectthrough the above operations and create a helical CT image of thesubject based on the at least one raw image.

FIG. 30 is a flowchart 300 of operations of the CT apparatus 100according to the sixth embodiment.

Referring to the flowchart 300, in operation 3010, the processor 110 ofthe CT apparatus 100 according to various embodiments may control thefirst rotation device 2721 to repeatedly perform a first operation ofbeing rotated in a first rotation direction by an angle of rotationdetermined based on the total number of the plurality of first lightsources 2731, 2732 and 2733 and the total number of the plurality ofsecond light sources 2734, 2735 and 2736 and a second operation of beingrotated in the second rotation direction by the determined angle ofrotation.

In operation 3020, the processor 110 according to various embodimentsmay control the second rotation device 2723 to repeatedly perform athird operation of being rotated by the determined angle of rotation inthe second rotation direction and a fourth operation of being rotated bythe determined angle of rotation in the first rotation direction. Thefirst operation of the first rotation device 2721 and the thirdoperation of the second rotation device 2723 may be performedsimultaneously, and the second operation of the first rotation device2721 and the fourth operation of the second rotation device 2723 may beperformed simultaneously.

In operation 3030, the processor 110 according to various embodimentsmay control the third rotation device 2725 to be rotated in the firstrotation direction at the same speed of rotation as the first rotationdevice 2721 and the second rotation device 2723.

In operation 3040, the processor 110 according to various embodimentsmay emit X-rays to the subject using one of the plurality of first lightsources 2731, 2732 and 2733 during the performance of the firstoperation by the first rotation device 2721, and emit X-rays to thesubject using one of the plurality of second light sources 2734, 2735and 2736 during the performance of the fourth operation by the secondrotation device 2723.

In operation 3050, the processor 110 according to various embodimentsmay detect X-rays passing through the subject by the detector 2740. Theprocessor 110 may create at least one raw image of the subject based onthe X-rays detected by the detector 2740. The processor 110 may create a3D image of the subject using the at least one raw image of the subject.

Other Embodiments

FIGS. 31A and 31B are diagrams illustrating a method of adjusting avisible area of a CT apparatus 100. FIG. 32 is a diagram showing amethod of adjusting a visible area using a plurality of light sources.The visible area may be an area in which X-rays passing through asubject O may be detected.

Generally, referring to FIG. 31A, in the CT apparatus 100 according tovarious embodiments, a visible area may be determined by a cone beamangle of a light source 3133 that is currently being operated among aplurality of light sources 3131, 3132, 3133 and 3134. When a subject Ois within a cone beam angle of a light source, the visible area may bedetermined by the angle of emission. In this case, a detector 3140 maybe located in the visible area to detect X-rays passing through thesubject O. For example, when the CT apparatus 100 may reduce the visiblearea to obtain a CT image of the subject O in a narrow area.

Referring to FIG. 31B, in order to obtain a CT image of a subject O in awide area, a visible area may be set to be wider than a cone beam angleof a light source. In this case, X-rays passing through the subject Omay be detected while moving the detector 3140 from a first position3140 a to a second position 3140 b. In this case, X-rays need notnecessarily be emitted a plurality of times to obtain a CT image of thesubject and the amount of X-rays exposed to the subject may decrease.

Referring to FIG. 32, a CT apparatus 100 according to variousembodiments may operate all of a plurality of light sources 3131, 3132,3133 and 3134 to adjust a visible area even when some of the pluralityof light sources 3131, 3132, 3133 and 3134 are not located at positionsfacing the detector 3140. In this case, a CT image of a subject O may beobtained without moving the detector 3140.

FIG. 33 is a diagram illustrating a CT apparatus 100 according tovarious embodiments of the present embodiment.

A power supply device 160 of the CT apparatus 100 according to variousembodiments may be located outside a gantry 120. When the power supplydevice 160 is located outside the gantry 120, stability may be increasedbecause the power supply device 160 does not rotate even when the gantry120 is rotated. The power supply device 160 may be connected to aplurality of light sources 130 through cables. The cable may be formedof a flexible material. The plurality of light sources 130 may besupplied with power from the power supply device 160 through a metalpart 135, and the vicinity of the metal part 135 may be molded by aninsulating material to increase stability. The insulating material maybe, for example, insulating oil or silicone.

FIGS. 34A to 35B are diagrams illustrating a CT apparatus 100 accordingto various embodiments of the present embodiment.

FIG. 34A is a cross-sectional view of an x-y plane of a gantry 3420 ofthe CT apparatus 100 according to various embodiments, and FIG. 34B is aschematic cross-sectional view of a y-z plane of the gantry 3420.

The CT apparatus 100 according to various embodiments may include agantry 3420 including a first rotation device 3421 and a second rotationdevice. A plurality of light sources 3430 may be arranged at regularintervals on the first rotation device 3421. A detector 3440 may bedisposed on the second rotation device and configured to surround thesecond rotation device. In this drawing, it is described that the totalnumber of the plurality of light sources 3430 is eight but the totalnumber of the plurality of light sources 3430 is not limited to eight.When the total number of the plurality of light sources 3430 is eight,the plurality of light sources 3430 may be arranged on the firstrotation device 3421 at intervals of 45 degrees.

According to various embodiments, positions of the plurality of lightsources 3430 on a z-axis may be different from each other. For example,the plurality of light sources 3430 may be arranged as shown in FIG.34B. As shown in FIGS. 35A and 35B, a structure of the first rotationdevice 3421 on which the plurality of light sources 3430 are arrangedmay be changed by applying a force to the first rotation device 3421 ina z-axis direction. When the first rotation device 3421 having thestructure shown in FIGS. 35A and 35B is used, the CT apparatus 100 mayobtain a helical CT image of a subject.

Although operations of processes, operations of methods, algorithms orthe like of flowcharts are described herein in a sequential order, theprocesses, the methods, the algorithms or the like may be configured tobe performed in any appropriate order. In other words, the processes,methods, and algorithms described above in the various embodiments ofthe present disclosure need not necessarily be performed in the ordersdescribed herein. Although some operations are described as beingperformed asynchronously, the operations may be performed simultaneouslyin other embodiments. In addition, it should not be understood thatexamples of a process illustrated in the drawings exclude other changesand modifications, any of the illustrated process or operations thereofare indispensable to at least one of various embodiments of the presentdisclosure, and the illustrated process is desirable.

While the foregoing methods have been described with respect toparticular embodiments, these methods may also be implemented ascomputer-readable codes on a computer-readable recording medium. Thecomputer-readable recoding medium includes any kind of data storagedevices that can be read by a computer system. Examples of thecomputer-readable recording medium include a read-only memory (ROM), arandom-access memory (RAM), a compact disc (CD)-ROM, a magnetic tape, afloppy disk, an optical data storage device, and the like. Thecomputer-readable recoding medium can be distributed to the computersystems connected through a network so that the computer-readable codescan be stored and executed in a distribution manner. Functionalprograms, codes, and code segments for implementing the foregoingembodiments can easily be inferred by programmers in the art to whichthe present disclosure pertains.

Although the technical spirit of the present disclosure has beendescribed by the examples described in some embodiments and illustratedin the accompanying drawings, it should be noted that varioussubstitutions, modifications, and changes can be made without departingfrom the scope of the present disclosure which can be understood bythose skilled in the art to which the present disclosure pertains. Inaddition, it should be noted that such substitutions, modifications andchanges are intended to fall within the scope of the appended claims.

What is claimed is:
 1. A computed tomography (CT) apparatus comprising:a gantry including a first rotation device and a second rotation devicewhich have a ring shape, share an axis of rotation, and are rotatableindependently of each other; a plurality of light sources provided atregular intervals on the first rotation device and configured to emitX-rays to a subject; a detector provided on the second rotation deviceand configured to detect X-rays passing through the subject; and one ormore processors, wherein the one or more processors are configured to:rotate the first rotation device in a first rotation direction by anangle of rotation determined based on a total number of the plurality oflight sources; emit X-rays to the subject by using at least one of theplurality of light sources and detect X-rays passing through the subjectby the detector during the rotation of the first rotation device in thefirst rotation direction; and rotate the first rotation device by thedetermined angle of rotation in a second rotation direction opposite tothe first rotation direction.
 2. The CT apparatus of claim 1, whereinthe one or more processors are configured to emit X-rays to the subjectby using at least one of the plurality of light sources and detectX-rays passing through the subject by the detector during the rotationof the first rotation device in the second rotation direction.
 3. The CTapparatus of claim 2, wherein the detector is configured to surroundinner sides of the second rotation device, and the one or moreprocessors are configured to control the plurality of light sources toalternately emit X-rays to the subject in units of a unit angle in apredetermined order during the rotation of the first rotation device inthe first rotation direction or the second rotation direction.
 4. The CTapparatus of claim 3, wherein the one or more processors are configuredto: create at least one raw image of the subject in response to thedetection of the X-rays passing through the subject by the detector; andcreate a three-dimensional (3D) image of the subject based on the atleast one raw image of the subject.
 5. The CT apparatus of claim 3,wherein the one or more processors are configured to rotate the secondrotation device by the determined angle of rotation in a same rotationdirection as the first rotation device during the rotation of the firstrotation device by the determined angle of rotation in the firstrotation direction or the second rotation direction.
 6. The CT apparatusof claim 2, further comprising a transfer unit on which the subject isloaded, wherein the one or more processors are configured to: move thetransfer unit by a predetermined distance in a direction of an axis ofrotation after the rotation of the first rotation device by thedetermined angle of rotation in the first rotation direction; and movethe transfer unit by the predetermined distance in the direction of theaxis of rotation after the rotation of the first rotation device by thedetermined angle of rotation in the second rotation direction.
 7. The CTapparatus of claim 6, wherein the one or more processors are configuredto repeatedly perform a predetermined number of times a cycle of:rotating the first rotation device by the determined angle of rotationin the first rotation direction; moving the transfer unit by thepredetermined distance in the direction of the axis of rotation afterthe rotation of the first rotation device by the determined angle ofrotation in the first rotation direction; rotating the first rotationdevice by the determined angle of rotation in the second rotationdirection; and moving the transfer unit by the predetermined distance inthe direction of the axis of rotation after the rotation of the firstrotation device in the second rotation direction.
 8. The CT apparatus ofclaim 2, further comprising a transfer unit on which the subject isloaded, wherein the one or more processors are configured to move thetransfer unit at a predetermined speed in a direction of an axis ofrotation during the rotation of the first rotation device in the firstrotation direction and the second rotation direction.
 9. The CTapparatus of claim 8, wherein the one or more processors are configuredto repeatedly perform a predetermined number of times a cycle of:rotating the first rotation device by the determined angle of rotationin the first rotation direction during the movement of the transfer unitat the predetermined speed in the direction of the axis of rotation; androtating the first rotation device by the determined angle of rotationin the second rotation direction during the movement of the transferunit at the predetermined speed in the direction of the axis ofrotation.
 10. The CT apparatus of claim 1, wherein the detector isdisposed in a region of the second rotation device, and the one or moreprocessors are configured to: rotate the second rotation device in thefirst rotation direction at a same speed of rotation as the firstrotation device during the rotation of the first rotation device in thefirst rotation direction and the second rotation direction; and emitX-rays to the subject by using one of the plurality of light sources anddetect X-rays passing through the subject by the detector during therotation of the first rotation device in the first rotation direction.11. The CT apparatus of claim 10, wherein the one or more processors areconfigured to repeatedly perform a predetermined number of times a cycleof: rotating the first rotation device by the determined angle ofrotation in the first rotation direction; emitting X-rays to the subjectby using at least one of the plurality of light sources and detectingX-rays passing through the subject by the detector during the rotationof the first rotation device in the first rotation direction; androtating the first rotation device by the determined angle of rotationin the second rotation direction, and wherein each time the cycle isrepeated, a light source to emit X-rays among the plurality of lightsources is changed in a predetermined order, and the predeterminednumber of times is determined based on the total number of the pluralityof light sources.
 12. The CT apparatus of claim 11, wherein the one ormore processors are configured to control an initial position of thesecond rotation device to cause the detector to be located at a positionfacing and corresponding to a first light source among the plurality oflight sources if X-rays are set to be emitted starting from the firstlight source based on the predetermined order at an initial stage. 13.The CT apparatus of claim 10, wherein the one or more processors areconfigured to control the plurality of light sources not to emit X-raysto the subject during the rotation of the first rotation device in thesecond rotation direction.
 14. The CT apparatus of claim 10, wherein theone or more processors are configured to: create at least one raw imageof the subject in response to the detection of the X-rays passingthrough the subject by the detector; and create a three-dimensional (3D)image of the subject based on the at least one raw image of the subject.15. The CT apparatus of claim 10, further comprising a transfer unit onwhich the subject is loaded, wherein the one or more processors areconfigured to move the transfer unit by a predetermined distance in adirection of an axis of rotation during the rotation of the firstrotation device in the first rotation direction.
 16. The CT apparatus ofclaim 10, further comprising a transfer unit on which the subject isloaded, wherein the one or more processors are configured to move thetransfer unit at a predetermined speed in a direction of an axis ofrotation during the rotation of the first rotation device in the firstrotation direction and the second rotation direction.
 17. The CTapparatus of claim 1, wherein the determined angle of rotation is avalue obtained by dividing 360 degrees by the total number of theplurality of light sources.
 18. The CT apparatus of claim 1, wherein alayout plan of the first rotation device and a layout plan of the secondrotation device, which are perpendicular to the axis of rotation, areparallel to each other.
 19. The CT apparatus of claim 1, wherein theplurality of light sources comprise X-ray sources using carbonnanotubes.
 20. The CT apparatus of claim 1, further comprising a powersupply device configured to supply a voltage to the plurality of lightsources, wherein the power supply device is provided outside the gantry.